3954 Vol. 10, 3954 –3964, June 15, 2004
`
`Clinical Cancer Research
`
`Report from the FDA
`
`Approval Summary for Bortezomib for Injection in the Treatment
`of Multiple Myeloma
`
`Peter F. Bross, Robert Kane, Ann T. Farrell,
`Sophia Abraham, Kimberly Benson,
`Margaret E. Brower, Sean Bradley,
`Jogarao V. Gobburu, Anwar Goheer,
`Shwu-Luan Lee, John Leighton, Cheng Yi Liang,
`Richard T. Lostritto, William D. McGuinn,
`David E. Morse, Atiqur Rahman,
`Lilliam A. Rosario, S. Leigh Verbois,
`Grant Williams, Yong-Cheng Wang, and
`Richard Pazdur
`Division of Oncology Drug Products, Center for Drug Evaluation and
`Research, United States Food and Drug Administration, Rockville,
`Maryland
`
`ABSTRACT
`Purpose: Multiple myeloma is a malignant plasma cell
`disorder accounting for about 10% of hematological malig-
`nancies. Despite treatment advances, including hematopoi-
`etic stem-cell transplantation to facilitate administration of
`high-dose cytotoxic chemotherapy, the median survival re-
`mains approximately 3 years and long-term remissions are
`rare. Bortezomib (Velcade, formerly known as PS-341; Mil-
`lennium Pharmaceuticals, Cambridge MA) is a dipeptide
`boronic acid that inhibits the 20S proteasome involved in the
`degradation of intracellular proteins, including those affect-
`ing cell cycle regulation in mammalian cells. Described
`herein are the analyses by the United States Food and Drug
`Administration (FDA) of clinical and nonclinical data sub-
`mitted in the New Drug Application. Chemistry manufac-
`turing and controls, animal toxicology, and biopharmaceu-
`tical data are described. The results of Phase I and Phase II
`clinical studies in patients with multiple myeloma are sum-
`marized. The marketing approval and postmarketing com-
`mitments are discussed.
`Results: Toxicology studies in the rat and monkey iden-
`tified hematological, lymphoid, cardiac, renal, gastrointesti-
`nal, and neurological toxicities of bortezomib. A steep dose-
`toxicity effect was noted at doses >0.9 mg/m2. Administration
`of doses >3.0 mg/m2 to monkeys resulted in cardiovascular
`collapse and death 12–14 h postdose. Histopathological evi-
`dence of axonal and myelin degeneration of dorsal root ganglia,
`peripheral nerves, and spinal cord were observed in monkeys
`and rodents; concurrent clinical observations included tremors
`and decreased activity.
`
`Received 12/22/03; revised 3/3/04; accepted 3/8/04.
`Requests for reprints: Peter F. Bross, United States Food and Drug
`Administration, HFM 755, 1401 Rockville Pike, Rockville, MD 20852.
`E-mail: bross@cber.fda.gov.
`
`Pharmacokinetic studies in patients with advanced ma-
`lignancies demonstrated that the mean elimination half-life
`after the first bortezomib dose varied from 9 to 15 h at doses
`ranging from 1.45 to 2.00 mg/m2. The drug is metabolized by
`cytochrome P450 –3A4, -2D6, -2C19, -2C9, and -1A2. Three
`Phase I studies were performed in a total of 123 patients with
`advanced malignancies. Dose-limiting toxicity included diar-
`rhea and sensory neurotoxicity. No dose-limiting hematological
`toxicity was reported.
`Safety and efficacy were evaluated in an open-label,
`Phase II study of 202 patients with multiple myeloma who
`had received at least two prior therapies and had demon-
`strated disease progression on their most recent therapy. A
`smaller dose finding study of 54 patients provided additional
`supportive information. Bortezomib was administered by
`i.v. bolus on days 1, 4, 8, and 11 in a 21-day cycle for up to
`eight cycles. The initial dose was 1.3 mg/m2 except for 28
`patients in the dose-finding study who received a 1.0 mg/m2
`dose. The primary study end point in this single-arm trial
`was response rate, easily measured and thought to correlate
`with clinical benefit in patients with myeloma. One hundred
`eighty-eight patients who met the inclusion criteria were
`included in the FDA efficacy analysis population. Complete
`responses (CRs) were observed in 5 patients and partial
`responses (PRs) in 47 patients for an overall response (OR)
`rate (OR ⴝ CR ⴙ PR) of 28%. The dose finding study of 54
`patients showed a higher response rate for patients given 1.3
`mg/m2 compared with 1.0 mg/m2 twice weekly for two of the
`3-week schedule, but the study was too small for statistical
`dose-response comparisons. The most commonly reported
`adverse events were asthenic conditions (including fatigue,
`malaise, and weakness) in 65%, nausea (64%), diarrhea
`(51%), appetite decreased (including anorexia; 43%), con-
`stipation (43%), thrombocytopenia (43%), peripheral neu-
`ropathy (37%, including peripheral sensory neuropathy and
`peripheral neuropathy aggravated), pyrexia (36%), vomit-
`ing (36%), and anemia (32%).
`Conclusions: The FDA granted marketing approval to
`Millennium Pharmaceuticals on May 13, 2003 for bort-
`ezomib for use as a single agent for the treatment of multiple
`myeloma in patients who have received at least two prior
`therapies and have demonstrated disease progression on the
`last therapy. Accelerated approval was based on a surrogate
`end point of response rate rather than clinical benefit, such
`as an improvement in survival. The recommended dose of
`bortezomib is 1.3 mg/m2 administered twice weekly for 2
`weeks (days 1, 4, 8, and 11) followed by a 10-day rest period
`(days 12–21). Accelerated approval was based on the results
`of two Phase II studies in a total of 256 patients and addi-
`tional Phase I safety information. Mandated Phase IV study
`commitments to characterize clinical efficacy and safety
`more precisely are discussed.
`
`Downloaded from
`
`on September 23, 2015. © 2004 American Association for
`clincancerres.aacrjournals.org
`Cancer Research.
`
`CFAD v. Anacor, IPR2015-01776
`ANACOR EX. 2012 - 1/12
`
`

`
`INTRODUCTION
`Multiple myeloma (MM) is a malignant plasma cell disor-
`der accounting for ⬃10% of hematological malignancies. There
`are approximately 45,000 people in the United States living with
`multiple myeloma and an estimated 14,600 new cases of mul-
`tiple myeloma are diagnosed each year.1 The reported incidence
`is 5 per 100,000 with a peak at age ⬃70 years; rates are higher
`in African Americans and in men (1). Multiple myeloma was
`first described in 1844; and in 1962, Bergsagel et al. (2) reported
`that melphalan, the phenylalanine derivative of nitrogen mus-
`tard, could induce remissions in about one-third of patients.
`Many cytotoxic regimens induce remissions, but effects on
`survival have been difficult to demonstrate despite increasing
`doses of conventional cytotoxic chemotherapy (3). Median
`overall survival does not exceed 3 years with conventional
`chemotherapy (4).
`High-dose chemotherapy followed by hematopoietic stem
`cell rescue has been shown to increase the percentage of com-
`plete remissions to almost 50% in selected patients (versus
`1–13% with conventional dose therapy), but the disease com-
`monly recurs (5, 6). High-dose chemotherapy may increase the
`CR rate and time-to-progression; however, myeloablative ther-
`apy has not consistently shown a survival improvement (7).
`Double autologous (tandem) transplantation has recently been
`shown to improve long-term survival
`in eligible patients
`less than 60 years old, but the majority of patients eventu-
`ally relapsed even after the double transplant (8). Subsequent
`treatment responses occur less frequently and are of shorter
`duration (9).
`Salmon et al. (10) first reported the efficacy of high-dose
`prednisone in this disease in 1967, and glucocorticoids are still
`a mainstay of myeloma therapy. Recent research has focused on
`other alternatives to cytotoxic chemotherapy. In 1999, Singhal
`et al. (11) reported durable responses with thalidomide in mul-
`tiple myeloma, and subsequent studies have confirmed its ac-
`tivity (12–13). In 2003, Richardson et al. (14) reported on the
`efficacy results of bortezomib, an inhibitor of the 20S protea-
`some, in advanced multiple myeloma. This article describes the
`analysis of clinical and nonclinical data that led to accelerated
`marketing approval of bortezomib for the treatment of multiple
`myeloma.
`
`RESPONSE CRITERIA IN MULTIPLE
`MYELOMA
`Multiple myeloma is characterized by the clonal prolifer-
`ation of plasma cells. Except in 1–2% of patients with nonse-
`cretory myeloma, an abnormal monoclonal immunoglobulin
`heavy- and/or light-chain paraprotein, known as M protein or M
`component, is readily quantifiable in the serum and/or urine of
`patients with multiple myeloma and has been used to measure
`the response to therapy and progression. In 1968 and 1973, the
`Chronic Leukemia and Myeloma Task Force of the National
`Cancer Institute published guidelines for the determination of
`
`1 Source of information, national program of cancer registries. Internet
`address: http://www.cdc.gov/cancer/npcr/uscs/report/.
`
`Clinical Cancer Research
`
`3955
`
`response in multiple myeloma, specifying a response parameter
`of 50% reduction in paraprotein measured by protein electro-
`phoresis (PEP) of serum (SPEP) or urine (UPEP; Ref. 15). The
`Southwest Oncology Group (SWOG) subsequently refined the
`remission criteria to require a 75% reduction in serum and a
`90% reduction in urine paraprotein (16, 17).
`CRs were rarely reported with earlier treatment options;
`however, the development of newer combination and dose-
`intensive therapy led to new proposals for assessing treatment
`response. In 1989, Gore et al. reported their response evaluation
`in a series of patients with myeloma treated with combination
`chemotherapy followed by high dose-melphalan and stem cell
`rescue (18). The Gore study reported a complete remission rate
`of 50% based on disappearance of M protein by PEP with the
`additional requirement of a confirmatory repeat electrophoresis
`finding 3 months later. Complete resolution of myeloma protein
`by PEP subsequently became a criterion for complete remission
`in the era of high-dose chemotherapy and stem-cell transplan-
`tation (7, 19 –21).
`In 1998, the European Group for Blood and Marrow Trans-
`plant (EBMT) proposed even stricter criteria for the assessment
`of CR in myeloma patients after high-dose therapy (22). These
`criteria include the complete absence of myeloma protein by
`immunofixation (IF) techniques as well as by PEP, and results
`must be confirmed at least 6 weeks later. In addition, bone
`marrow plasmacytosis must be reduced to less than 5%. Ab-
`sence of serum and urine paraprotein measured by IF has
`recently been used to define CRs for both conventional and
`high-dose regimens (23, 24, 12). Lahuerta et al. (25) published
`a retrospective study suggesting that complete remission by
`immunofixation electrophoresis status is a more sensitive pre-
`dictor of survival and time to progression than complete remis-
`sion by PEP. Differences among response categories are sum-
`marized in Table 1.
`
`THE PROTEASOME PATHWAY
`The ubiquitin-proteasome pathway is thought to play a
`critical role in the degradation of proteins involved in cell cycle
`control and tumor growth. A complex enzyme cascade first
`marks proteins destined for degradation by the covalent addition
`
`Table 1 Response criteria used in the efficacy analysis
`
`Reduction of M
`protein required
`
`SPEP
`
`UPEP
`
`IFa
`
`Response category
`EBMT
`CRb
`100%
`100%
`Negative
`90%
`50%
`NR
`PR
`50%
`25%
`NR
`MR
`SWOG remissionc
`90%
`75%
`NR
`a IF, immunofixation; M protein, myeloma protein; SPEP, serum
`protein electrophoresis; UPEP, urine protein electrophoresis; EBMT,
`European Group for Blood and Marrow Transplant; CR, complete
`response; PR, partial response; NR, not required; MR, minimum re-
`sponse; SWOG, Southwest Oncology Group.
`b EBMT CR also required ⬍5% plasma cells in bone marrow, after
`Blade et al. (22).
`c SWOG remission, after Alexanian et al. (16) and Salmon et al. (17).
`
`Downloaded from on September 23, 2015. © 2004 American Association forclincancerres.aacrjournals.org
`
`
`
`Cancer Research.
`
`ANACOR EX. 2012 - 2/12
`
`

`
`3956 Bortezomib in Multiple Myeloma
`
`of multiple molecules of ubiquitin (26). The proteasome hydro-
`lyzes only those proteins that have been marked for destruction
`by this ubiquitin enzyme cascade (27, 28). The 20S proteasome,
`the core component of the proteasome complex, is composed of
`four subunits forming a hollow cylinder that has multiple pro-
`teolytic sites on the interior wall (29). The proteasome-complex
`degrades proteins as it moves them through this cylinder. This
`20S proteasome must first bind to various other large proteins
`known as activators (PA700 and PA28 are examples) to form
`proteasome-activator complexes before it can hydrolyze the
`ubiquitin-bound protein substrates. These activators can bind to
`form different complexes, each with different protein substrate
`specificity. The most frequently studied proteasome complex is
`the 26S proteasome, a large molecule heterotrimer formed by
`the 20S proteasome and two PA700 activators (30 –33). The
`proteasome can affect cell division through ubiquination and
`degradation of inhibitory proteins through the regulation of
`nuclear transcription factors (34 –38). Evidence suggests that the
`inhibition of the proteasome can act through multiple mecha-
`nisms leading to an arrest of cell growth. Inhibition of the
`proteasome may also have other consequences. Limited in vitro
`research suggests that the inhibition of the proteasome pathway
`might lead to the accumulation of abnormal proteins, including
`prion-related protein (PrP), as demonstrated in transfected neu-
`ronal cell lines (39). The clinical consequences of this protein
`accumulation are unknown.
`
`BORTEZOMIB (PS-341, VELCADE)
`The search for molecules that could inhibit the 20S pro-
`teasome in vitro led to the discovery of bortezomib (Velcade,
`PS-341; Millennium Pharmaceuticals, Inc., Cambridge, MA), a
`small, dipeptide boronic acid that reversibly inhibits the chy-
`motrypsin-like proteolytic activity site of the 20S proteasome of
`mammalian cells (40). Bortezomib exhibits cytotoxic, growth-
`inhibitory, and antitumor activities in several in vitro and in vivo
`assay systems and binds to the proteasome at lower concentra-
`tions than it does to other tested proteases. In replicating cells in
`vitro, bortezomib appears to cause cell cycle arrest at the tran-
`sition of G2-M, and the inhibited cells then initiate apoptosis
`(41). In the standard National Cancer Institute panel of 60
`human cell lines, bortezomib inhibited cell growth and, in some
`cases, was cytotoxic for human tumor cells. The average IC50 of
`bortezomib across the 60 cell lines was 3.8 nM. In athymic mice
`implanted with both the HT-29 human colon and the PC-3
`human prostate-tumor xenograft models, bortezomib given i.v.
`weekly for 4 weeks (3 mg/m2) decreased tumor volume by up to
`50 and 65%, respectively. Resistance to bortezomib cytotoxicity
`has been noted over time in vitro. This resistance is probably not
`mediated by overexpression of
`transmembrane molecular
`pumps, such as the multidrug resistance protein.
`After in vivo dosing, inhibition of proteasome activity,
`measured in lysate from whole blood from animals or humans,
`recovers to normal in about 48 –72 h (42). Repeat dosing causes
`greater inhibition compared with a single dose at the same level
`(about 30% after a single dose compared with almost 99% after
`seven daily doses). Inhibition could be detected in tissue from
`colon, muscle, prostate, and liver but not in the testes or brain of
`rodents. The inhibition in the liver was significantly greater than
`
`in WBCs. Thus far, there is no evidence of a relationship
`between ex vivo measurements of proteasome inhibition and
`clinical efficacy.
`Bortezomib inhibited the degradation of cytochrome
`P450 –2E1 by proteasomes after ethanol induction, thus prevent-
`ing the return of intracellular expression of the enzyme to
`constitutive levels (43). Other cytochromes P450 may also be
`degraded by proteasomes after induction (44). Bortezomib has
`the potential to modify the metabolism of a broad range of
`chemicals by changing the intracellular concentration of cyto-
`chrome P-450 (45). Thus, proteasome inhibition by bortezomib
`may modify a patient’s exposure to drugs that are metabolized
`by cytochrome P-450.
`
`CHEMISTRY
`Bortezomib is a modified dipeptide boronic acid. The drug
`substance exists in its cyclic anhydride form in the solid state as
`a trimeric boroxine. The product is provided as a mannitol
`boronic ester that, in reconstituted form, exists in equilibrium
`with its hydrolysis product, the monomeric boronic acid. The
`chemical name for the monomeric form is [(1R)-3-methyl-1-
`{[(2S)-1-oxo-3-phenyl-2-[(pyrazinylcarbonyl)amino]propyl]-
`amino}butyl]boronic acid. The molecular weight is 384.24, and the
`molecular formula is C19H25BN4O4. The solubility of bortezomib,
`as the monomeric boronic acid, in water is 3.3–3.8 mg/ml in a pH
`range of 2–6.5. Bortezomib is available for i.v. injection as a sterile
`lyophilized powder in single-dose vials containing 3.5 mg bort-
`ezomib and 35 mg mannitol, USP. In this form, the drug product is
`stable and can be stored at controlled room temperature. The
`lyophilized powder drug product is reconstituted with 0.9% NaCl
`to a final concentration of 1 mg/1 ml before injection. The chemical
`structure is shown in Fig. 1.
`
`TOXICOLOGY
`Traditional
`toxicological and toxicokinetic parameters,
`neuropathological evaluations, and proteasome activity determi-
`nations were examined. Bortezomib was administered to rats as
`a single dose and twice weekly for 2 weeks and for 26 weeks.
`Bortezomib was poorly tolerated when administrated daily, even
`at very low doses. Nonclinical tolerability studies suggested that
`intermittent dosing permitted more prolonged dosing regimens
`by allowing a return toward baseline of 20S proteasome activity
`before the subsequent dose. In the 9-cycle 26-week rat study,
`
`Fig. 1 Bortezomib structure. Bortezomib is a modified dipeptide bo-
`ronic acid derived from leucine and phenylalanine.
`
`Downloaded from on September 23, 2015. © 2004 American Association forclincancerres.aacrjournals.org
`
`
`
`Cancer Research.
`
`ANACOR EX. 2012 - 3/12
`
`

`
`Clinical Cancer Research
`
`3957
`
`drug-related mortality was observed at ⱖ0.9 mg/m2 (days 23–
`180) and was due primarily to hematopoietic and lymphoid
`system depletion, along with gastrointestinal hyperplasia and
`necrosis. Histopathological changes were observed in the heart,
`liver, lung, kidney, sciatic nerve (necrosis), and spinal cord; in
`general, similar findings albeit with less severity were observed
`in scheduled-death animals. Animals who were dosed at ⱖ0.9
`mg/m2 and who survived to week 26 (end of treatment) exhib-
`ited various forms of neurotoxicity including degeneration of
`dorsal root ganglia, peripheral nerves, and spinal cord. Nephro-
`toxicity, including eosinophilic casts, inflammation, hypertro-
`phy, tubular dilation, and glomerulonephritis was observed at 26
`weeks of treatment at doses ⱖ0.6 mg/m2; a comparable inci-
`dence of tubular dilation was observed after 8 weeks of recovery
`in males. Cardiac histopathological changes included increased
`incidence of perivascular necrosis, myocardial degeneration,
`hemorrhage, and inflammation. Thrombocytopenia was ob-
`served at all dose levels. After the 8-week recovery interval,
`myocardial inflammation, cardiac necrosis, and tubular dilation
`of the kidney (males only) persisted. There appeared to be some
`indication of reversibility of other findings at this time.
`Bortezomib was administered to monkeys as a single dose,
`a daily dose for 13 days, twice-weekly for 2 weeks, and twice-
`weekly for 4- and 13-three week cycles. In the 13-cycle monkey
`study, bortezomib-related mortality was observed at dosages
`ⱖ0.9 mg/m2. Findings included severe anemia, dehydration,
`gastrointestinal diffuse mucosal hyperplasia, thrombocytopenia,
`neurotoxicity, and cardiotoxicity. There was an increased inci-
`dence of clinically observable findings, typically associated with
`neurotoxicity, in treated animals when compared with controls
`during bortezomib administration. The frequency of histopatho-
`logical findings demonstrating neurotoxicity was reduced after 8
`weeks of recovery.
`Clinical neurotoxicity was reported in monkeys, rats, and
`mice; findings included nerve degeneration of dorsal root gan-
`glia, peripheral nerves, dorsal spinal roots and dorsal tracts of
`the spinal cord at ⱖ0.6 mg/m2 (one-half of the recommended
`clinical dose of 1.3 mg/m2). Histopathological incidence of
`neurotoxic effects in monkeys appeared greater compared with
`that in rodents. Clinical observations included tremors and re-
`duced activity in monkeys; rats also exhibited reduced activity.
`Nephrotoxicity was observed at doses ⱖ0.9 g/m2 in monkeys;
`males appeared to be more susceptible. Lymphoid atrophy
`and/or necrosis occurred in thymus, spleen, lymph nodes, and
`gut-associated lymphoid tissue. In addition, necrosis, atrophy,
`and hyperplasia of the gastrointestinal tract were observed in
`monkeys surviving to 38 weeks.
`Dose- and schedule-dependent changes in AUC (area under
`the curve) and Cmax (maximum concentration) occurred in both
`species. Drug exposure with increasing dose was more linear in
`monkeys compared with rodents; the explanation for this dif-
`ference is unknown. After multiple doses, a decrease in clear-
`ance resulted in an increase in the terminal elimination half-life
`(t1/2) and AUC (3– 4-fold) in rats and cynomolgus monkeys,
`suggesting drug accumulation. Even though there were no gen-
`der differences in systemic exposure, it appears that female
`decedent rats exhibited a greater degree of toxicity compared
`with males based on the number and types of lesions, as well as
`on the total number of unscheduled deaths. Using an ex vivo 20S
`
`proteasome assay to measure inhibition of the chymotrypsin-
`like proteolytic activity in whole blood cells, proteasome inhi-
`bition increased with dose and returned to baseline by about
`72 h in rats and monkeys. After a single dose of [14C]bort-
`ezomib, bortezomib-related radioactivity was eliminated slowly
`from tissues (with highest concentrations in liver and kidneys);
`incomplete recovery of administered radioactivity in rats and
`monkeys suggests extensive tissue distribution and retention of
`bortezomib and its metabolites. Radioactivity was detected in
`the brain of monkeys but not of rats.
`Cardiovascular safety pharmacology studies conducted in
`cynomolgus monkeys showed that the administration of dosages
`ⱖ3.0 mg/m2 resulted initially in physiologically significant
`heart rate elevations, then profound progressive hypotension,
`bradycardia, and death 12–14 h postdose. Additional studies in
`monkeys showed bortezomib increased heart rate (ⱖ1.2 mg/
`m2), decreased mean arterial pressure (ⱖ2.4 mg/m2), increased
`ventricular contractility (ⱖ3.6 mg/m2), and increased cardiac
`output (ⱖ3.6 mg/m2). Mortality was not reported in this study;
`however, this study is inadequate to address drug-associated
`mortality observed in the previous studies because these mon-
`keys were sacrificed before signs of terminal hypotension and
`imminent mortality occurred. Bortezomib-related radioactivity
`was distributed to the myocardium. Histopathological findings
`in repeat-dose monkey studies showed cardiac necrosis at doses
`ⱖ0.9 mg/m2. Whether the observed cardiac effects are depend-
`ent on local drug disposition and/or direct drug-myocardial
`toxicity is unknown.
`Bortezomib exhibited clastogenic activity in the in vitro
`chromosomal aberration assay using Chinese hamster ovary
`cells but was not genotoxic when tested in the in vitro mutage-
`nicity assay (Ames test) or the in vivo micronucleus assay.
`Teratological effects were examined in the rat and the rabbit. No
`formal evaluation of fertility or peri- and postnatal development
`(Segments I and III, respectively) were conducted. Pregnant
`rabbits given bortezomib during organogenesis at a dose of 0.6
`mg/m2 experienced significant postimplantation loss and a de-
`creased number of live fetuses at minimally maternally toxic
`doses. Live fetuses also showed significant decreases in fetal
`weight. This dose is approximately one-half the clinical dose
`(1.3 mg/m2). On the basis of embryo lethality findings in rats
`and rabbits, and the effects on primary and secondary sex organs
`observed in the 6-month rat study and the 9-month monkey
`toxicity studies, bortezomib is likely to have an adverse effect
`on pregnancy. However, bortezomib was not teratogenic in rats
`and rabbits at the highest dose tested, 0.5 mg/m2 in the rat and
`0.6 mg/m2 in the rabbit, when administered during organogen-
`esis. These dosages also are approximately one-half of the
`human clinical dose. Bortezomib is labeled “Pregnancy category
`D;” because of the potential of significant adverse effects on the
`developing fetus, women are strongly advised not to become
`pregnant while taking bortezomib.
`
`CLINICAL STUDIES SUPPORTING APPROVAL
`Three Phase I dose finding trials of bortezomib as mono-
`therapy were performed in a total of 123 patients with a variety
`of advanced malignancies. Two Phase II studies were performed
`in 256 patients with multiple myeloma who had not achieved a
`
`Downloaded from on September 23, 2015. © 2004 American Association forclincancerres.aacrjournals.org
`
`
`
`Cancer Research.
`
`ANACOR EX. 2012 - 4/12
`
`

`
`3958 Bortezomib in Multiple Myeloma
`
`response to, or who had relapsed after, initial therapy. If patients
`progressed after two cycles or experienced no improvement
`after four cycles, dexamethasone 20 mg daily p.o. for 2 days was
`added to each bortezomib dose. An extension studies allowed
`continued therapy in those patients who appeared to benefit. The
`extension study provided safety information on longer-term
`therapy and efficacy information on response duration.
`
`PHASE I STUDIES
`The Phase I studies were performed in patients with ad-
`vanced malignancies using weekly and twice-weekly dosing
`schedules. Weekly dosing was associated with dose-limiting
`toxicities of diarrhea, hypotension, tachycardia, and syncope
`with doses ⬎1.6 mg/m2. The maximum tolerated dose was
`found to be 1.3 mg/m2 when given twice-weekly in the first 2
`weeks of a 3-week cycle. This compares with a maximum
`tolerated dose of 1.04 mg/m2 when given twice-weekly for the
`first 4 weeks in a 6-week cycle. At the 1.3 mg/m2 dose, the 1-h
`mean percentage proteasome inhibition measured in patients’
`WBCs on day 1, cycle 1, is higher than the corresponding value
`at cycle 7 (70.5 versus 55%). The relationship between protea-
`some inhibition and dose suggests that the optimal bortezomib
`dose may be between 1.0 mg/m2 and 1.3 mg/m2. The twice-
`weekly dosing each 21-day cycle was selected because ⬃25%
`more drug could be tolerated.
`
`PHASE II CLINICAL STUDIES
`Two Phase II studies assessed the safety and efficacy of
`bortezomib. A small, open-label, randomized Phase II dose-
`finding study, Clinical Response and Efficacy Study of bort-
`ezomib in the Treatment of
`relapsing multiple myeloma
`(CREST) was performed in 54 patients with relapsed multiple
`myeloma to provide some dose-response data (46). The 1.3-
`mg/m2 dose was compared with the 1.0-mg/m2 dose using a
`21-day cycle with treatment given during the first 2 weeks. The
`sponsor chose the higher dose because of a somewhat higher
`overall response rate that included minimal responders. The
`larger Study of Uncontrolled Multiple Myeloma managed with
`proteasome Inhibition Therapy (SUMMIT) was an open-label,
`single-arm, multicenter study of patients who had received at
`least two prior therapies and demonstrated disease progression
`on their most recent therapy (15). Patients were eligible if they
`had relapsed after a response to standard first-line chemotherapy
`(e.g., vincristine-doxorubicin-dexamethasone or melphalan-
`prednisone) or high-dose chemotherapy, and were refractory
`(i.e., failure to achieve at least CR, PR, or stable disease) to their
`most recent chemotherapy. Primary refractory patients were not
`enrolled.
`Bortezomib 1.3 mg/m2 was administered by i.v. bolus over
`3–5 s on days 1, 4, 8, and 11 in a 21-day cycle. A maximum of
`eight cycles (24 weeks) was planned, but treatment could be
`continued for responding patients in a continuation study. Treat-
`ment was withheld in patients experiencing ⱖ grade 3 nonhe-
`matological or grade 4 hematological toxicities until resolution
`or grade 1 was attained, and treatment was then resumed at the
`next lower dose level, either 1.0 or 0.7 mg/m2. Patients with
`progressive disease after completing two cycles or who experi-
`enced no response after four cycles could be treated with the
`
`addition of dexamethasone, 20 mg p.o. (each day of, and the day
`after, bortezomib administration, i.e., 40 mg with each dose).
`These patients were analyzed separately for efficacy and were
`not included in the primary analysis. Safety assessments per-
`formed during treatment
`included monitoring for adverse
`events, a directed questionnaire for neurological toxicities, spe-
`cialized neurological testing, and clinical examinations.
`The SUMMIT trial enrolled 202 patients. Eighty-four %
`had IgG or IgA myeloma and advanced disease at diagnosis, and
`80% had a Karnofsky performance-status score ⱖ80. The mean
`age was 59 years; 81% were white, 10% were black, and 60%
`were male. Ninety-two % had been treated with three or more of
`the major classes of agents used to treat myeloma (steroids,
`alkylating agent, thalidomide, or anthracyclines). The median
`number of previous therapies was six (range, 2–15). Sixty-four
`% had received high-dose therapy and stem-cell transplantation.
`Five patients had not been treated with cytotoxic chemotherapy;
`these were excluded from the efficacy analysis. In comparison,
`the CREST study enrolled a less heavily pretreated population;
`the mean number of prior therapies was three, compared with
`six in the larger study. The mean Karnofsky performance-status
`score was also higher in the CREST study; otherwise, the trial
`characteristics were similar. Baseline patient and disease char-
`acteristics for both studies are summarized in Table 2.
`
`RESULTS
`The primary objective of the Phase II studies was the
`determination of overall response rate (CR ⫹ PR ⫹ minimal
`response). Responses were assigned by an Independent Review
`Committee based on the EBMT criteria described above (sec-
`tion “Response Criteria in Multiple Myeloma”). PRs required a
`50% reduction in serum M protein and 90% reduction in urine
`M protein. Additional response analyses including remission by
`SWOG criteria and rate of complete resolution of M protein by
`PEP were performed to facilitate comparison with other reports
`of available therapy (see Table 1.) Minimal responses were not
`included in the United States Food and Drug Administration
`(FDA) analysis because these responses were deemed less likely
`to predict clinical benefit. All of the responses required confir-
`mation at 6 weeks by protein electrophoresis (CRs required
`repeat IF also.)
`Fifty-four patients were enrolled in the CREST study. The
`response rate (CR⫹PR) was 38% in the 1.3-mg/m2 group com-
`pared with 30% in the 1.0-mg/m2 group. One patient in each
`group experienced a CR by EBMT criteria, and two additional
`patients in the 1.0-mg/m2 group experienced complete resolu-
`tion of myeloma M protein by PEP. If minimal responses were
`included, the (CR ⫹ PR ⫹ minimal response) rate was 50% in
`the 1.3-mg/m2 group compared with 33% in the 1.0-mg/m2
`group. This observation of a higher response rate led the sponsor
`to recommend the higher dose for further study, although the
`numbers were too small for statistical dose-response compari-
`sons.
`In the SUMMIT study, the FDA analysis identified 188
`patients of the 202 enrolled who had evaluable disease and who
`fulfilled all eligibility criteria. The study population included
`patients with numerous adverse prognostic features including ␤
`2
`microglobulin levels above 4 mg/liter, cytogenetic abnormali-
`
`Downloaded from on September 23, 2015. © 2004 American Association forclincancerres.aacrjournals.org
`
`
`
`Cancer Research.
`
`ANACOR EX. 2012 - 5/12
`
`

`
`Table 2 Summary of characteristics of patients enrolled in the
`bortezomib Phase II studies in multiple myeloma
`
`CREST dose level
`
`1.0 mg/m2
`(n ⫽ 28)
`
`1.3 mg/m2
`(n ⫽ 26)
`
`SUMMITa
`dose level
`1.3 mg/m2
`(n ⫽ 202)
`
`Characteristic
`
`14 (50)
`14 (50)
`
`25 (89)
`3 (11)
`0
`0
`
`65
`39, 82
`
`2 (7)
`1 (4)
`8 (29)
`17 (61)
`
`9 (35)
`17 (65)
`
`20 (77)
`3 (12)
`2 (8)
`1 (4)
`
`61
`30, 84
`
`2 (8)
`2 (8)
`8 (31)
`14 (54)
`
`2
`2
`⬍0.5–20 ⬍0.5–8
`7/24
`11/23
`2/7
`3/11
`14/24
`11/23
`
`121 (60)
`81 (40)
`
`164 (81)
`21 (10)
`5 (2)
`12 (6)
`
`59
`34, 84
`
`19 (10)
`21 (11)
`74 (38)
`82 (42)
`
`4
`1–18
`60/172
`26/172
`138
`
`Clinical Cancer Research
`
`3959
`
`CRs or PRs to bortezomib monotherapy (see Table 3.) Among
`the 47 PRs, there were 12 patients who exhibited complete
`resolution of M protein by PEP but not by IF.
`In addition to the protocol-specified response analysis
`(EBMT), a separate analysis by SWOG criteria showed clinical
`remission criteria were fulfilled by 33 patients