Document:

Exhibit 4.6

                               AMENDMENT NO. 1
                                     TO
                            NN BALL & ROLLER, INC.
                              STOCK INCENTIVE PLAN

      As adopted by the Board of Directors on February 26, 1999 and approved by
the stockholders of the Company on May 13, 1999 as required in Section 23 of the
Stock Incentive Plan, the NN Ball & Roller, Inc. Stock Incentive Plan is hereby
amended as follows:

      Section 4(a) shall be amended in its entirety to read as follows:

            "4.   NUMBER AND SOURCE OF SHARES SUBJECT TO THE PLAN.

                  (a)   The Company may grant Awards under the Plan with
                        respect to not more that 1,625,000 Shares, (subject,
                        however, to adjustment as provided in Section 22
                        hereof), which Shares may be provided from any or a
                        combination of the Company's treasury, the issuance
                        of authorized but unissued Shares, and/or the
                        purchase of outstanding Shares in the open market or
                        in private transactions.

      Except as expressly amended by the Board of Directors and stockholders as
set forth above, the NN Ball & Roller, Inc. Stock Incentive Plan is hereby
ratified and confirmed in all respects.

      IN WITNESS WHEREOF, NN Ball & Roller, Inc., acting by and through its
officer hereunto duly authorized has executed this Amendment as of the 13th
day of May, 1999.

                              NN BALL & ROLLER, INC.

                              By:  /s/   RODERICK R. BATY
                              Name:   Roderick R. Baty
                              Title:  Chief Executive Officer and President

                                       10<PAGE>

                                                                   EXHIBIT 10.48
                                                                   -------------

                              PURCHASE AGREEMENT

          THIS AGREEMENT is made as of the __ day of November, 2000, by and
among Curis, Inc. (the "Company"), a corporation organized under the laws of the
State of Delaware, with its principal offices at 61 Moulton Street, Cambridge,
Massachusetts 02138, and the purchaser whose name and address is set forth on
the signature page hereof (the "Purchaser").

          IN CONSIDERATION of the mutual covenants contained in this Agreement,
the Company, and the Purchaser agree as follows:

          SECTION 1.  Authorization of Sale of the Shares.  Subject to the terms
                      -----------------------------------
and conditions of this Agreement, the Company has authorized the sale of up to
5,200,000 shares (the "Shares") of common stock, par value $0.01 per share (the
"Common Stock"), of the Company.

          SECTION 2.  Agreement to Sell and Purchase the Shares.  At the Closing
                      -----------------------------------------
(as defined in Section 3), the Company will sell to the Purchaser, and the
Purchaser will buy from the Company, upon the terms and conditions hereinafter
set forth, the number of Shares (at the purchase price) shown below:

                              Price Per
       Number to Be           Share In                 Aggregate
         Purchased             Dollars                  Price
       ---------------      -------------             -----------

          The Company proposes to enter into substantially the same form of
purchase agreement with certain other investors (the "Other Purchasers") and
expects to complete sales of the Shares to them. The Purchaser and the Other
Purchasers are hereinafter sometimes collectively referred to as the
"Purchasers," and this Agreement and the agreements executed by the Other
Purchasers are hereinafter sometimes collectively referred to as the
"Agreements."  The term "Placement Agent" shall mean Prudential Vector
Healthcare Group.

          SECTION 3.  Delivery of the Shares at the Closing.  The completion of
                      -------------------------------------
the purchase and sale of the Shares (the "Closing") shall occur as soon as
practicable, but no later than two business days, following notification by the
Securities and Exchange Commission (the "Commission") to the Company of the
Commission's willingness to declare effective the registration statement to be
filed by the Company pursuant to Section 7.1 hereof (the "Registration
Statement") at a place (the "Closing Date") to be agreed upon by the Company and
the Placement Agent.  The Company will promptly notify the Purchasers by
facsimile transmission or otherwise of the date, place and time of the Closing.

          At the Closing, the Company shall deliver to the Purchaser one or more
stock certificates registered in the name of the Purchaser, or in such nominee
name(s) as designated by the Purchaser in writing, representing the number of
Shares set forth in Section 2 above and
<PAGE>

bearing an appropriate legend referring to the fact that the Shares were sold in
reliance upon the exemption from registration under the Securities Act of 1933,
as amended (the "Securities Act") provided by Section 4(2) thereof and Rule 506
thereunder. Upon receipt of the Purchaser's Certificate of Subsequent Sale
attached hereto as Appendix II, share certificates bearing a restrictive legend
may be exchanged by the transfer agent for share certificates without the legend
(or a credit for such shares to book-entry accounts maintained by the transfer
agent). The name(s) in which the stock certificates are to be registered are set
forth in the Stock Certificate Questionnaire attached hereto as part of Appendix
I. The Company's obligation to complete the purchase and sale of the Shares and
deliver such stock certificate(s) to the Purchaser at the Closing shall be
subject to the following conditions, any one or more of which may be waived by
the Company: (a) receipt by the Company of same-day funds in the full amount of
the purchase price for the Shares being purchased hereunder; (b) completion of
the purchases and sales under the Agreements with all of the Other Purchasers
and (c) the accuracy of the representations and warranties made by the
Purchasers and the fulfillment of those undertakings of the Purchasers to be
fulfilled prior to the Closing. The Purchaser's obligation to accept delivery of
such stock certificate(s) and to pay for the Shares evidenced thereby shall be
subject to the following conditions, any one or more of which may be waived by
the Purchaser: (a) the Commission has notified the Company of the Commission's
willingness to declare the Registration Statement effective on or prior to the
75th day after the date such Registration Statement was filed by the Company;
(b) each of the representations and warranties of the Company made herein shall
be true and correct in all material respects at the Closing Date with the same
effect as though made at and as of such date; and (c) the fulfillment in all
material respects of those undertakings of the Company to be fulfilled prior to
Closing. The Purchaser's obligations hereunder are expressly not conditioned on
the purchase by any or all of the Other Purchasers of the Shares that they have
agreed to purchase from the Company.

          SECTION 4.  Representations, Warranties and Covenants of the Company.
                      ---------------------------------------------------------
The Company hereby represents and warrants to, and covenants with, the Purchaser
as follows:

          4.1. Organization and Qualification.  The Company is a corporation
               ------------------------------
duly organized, validly existing and in good standing under the laws of its
jurisdiction of incorporation and the Company is qualified to do business as a
foreign corporation in each jurisdiction in which qualification is required,
except where failure to so qualify would not have a material adverse effect on
the Company's condition (financial or otherwise), properties, business,
prospects or results of operations taken as a whole (a "Company Material Adverse
Effect"). The Company has no subsidiaries.

          4.2. Authorized Capital Stock.  Except as disclosed in or
               ------------------------
contemplated by the confidential private placement memorandum dated October 23,
2000 prepared by the Company, including all exhibits, supplements and amendments
thereto (the "Offering Materials"), the Company had authorized and outstanding
capital stock as set forth under the heading "Capitalization" in the Offering
Materials as of the date set forth therein; the issued and outstanding shares of
the Company's Common Stock have been duly authorized and validly issued, are
fully paid and nonassessable, have been issued in compliance with all federal
and state securities laws, were not issued in violation of or subject to any
preemptive rights or other rights to subscribe for or purchase securities, and
conform in all material respects to the

                                       2
<PAGE>

description thereof contained in the Offering Materials. Except as disclosed in
or contemplated by the Offering Materials, the Company does not have outstanding
any options to purchase, or any preemptive rights or other rights to subscribe
for or to purchase, any securities or obligations convertible into, or any
contracts or commitments to issue or sell, shares of its capital stock. The
description of the Company's stock, stock bonus and other stock plans or
arrangements and the options or other rights granted and exercised thereunder,
set forth in the Offering Materials accurately and fairly presents the
information required to be shown with respect to such plans, arrangements,
options and rights.

          4.3.  Issuance, Sale and Delivery of the Shares.  The  Shares have
                -----------------------------------------
been duly authorized and, when issued, delivered and paid for in the manner set
forth in this Agreement, will be duly authorized, validly issued, fully paid and
nonassessable, and will conform in all material respects to the description
thereof set forth in the Offering Materials.  No preemptive rights or other
rights to subscribe for or purchase exist with respect to the issuance and sale
of the Shares by the Company pursuant to this Agreement.  No stockholder of the
Company other than the Purchasers has any right (which has not been waived or
has not expired by reason of lapse of time following notification of the
Company's intent to file the Registration Statement) to require the Company to
register the sale of any shares owned by such stockholder under the Securities
Act in the Registration Statement.  No approval or authority of the stockholders
or the Board of Directors of the Company not obtained as of the date hereof will
be required for the issuance and sale of the Shares to be sold by the Company as
contemplated herein.

          4.4.  Due Execution, Delivery and Performance of the Agreements.  The
                ---------------------------------------------------------
Company has full legal right, corporate power and authority to enter into the
Agreements and perform the transactions contemplated hereby.  The Agreements
have been duly authorized, executed and delivered by the Company.  The Company
now holds all material licenses, certificates and permits from state, federal
and other regulatory authorities which are necessary for the conduct of its
business as presently conducted, except where the failure to hold any such
licenses, certificates and permits would not have a Company Material Adverse
Effect.  The making and performance of the Agreements by the Company and the
consummation of the transactions herein contemplated will not violate any
provision of the organizational documents of the Company and will not result in
the creation of any lien, charge, security interest or encumbrance upon any
assets of the Company pursuant to the terms or provisions of, and will not
conflict with, result in the breach or violation of, or constitute, either by
itself or upon notice or the passage of time or both, a default under any
agreement, mortgage, deed of trust, lease, franchise, license, indenture, permit
or other instrument to which the Company is a party or by which the Company or
its properties may be bound or affected and in each case which would have a
Company Material Adverse Effect or, to the Company's knowledge, any statute or
any authorization, judgment, decree, order, rule or regulation of any court or
any regulatory body, administrative agency or other governmental body applicable
to the Company or its properties. No consent, approval, authorization or other
order of any court, regulatory body, administrative agency or other governmental
body is required for the execution and delivery of this Agreement or the
consummation of the transactions contemplated by this Agreement, except for
compliance with the Blue Sky laws and federal securities laws applicable to the
offering of the Shares.  Upon their execution and delivery, and assuming the
valid execution thereof by the respective Purchasers, the Agreements will
constitute valid and binding obligations of the Company,

                                       3
<PAGE>

enforceable in accordance with their respective terms, except as enforceability
may be limited by applicable bankruptcy, insolvency, reorganization, moratorium
or similar laws affecting creditors' and contracting parties' rights generally
and except as enforceability may be subject to general principles of equity
(regardless of whether such enforceability is considered in a proceeding in
equity or at law) and except as the indemnification agreements of the Company in
Section 7.3 hereof may be legally unenforceable.

          4.5.  Accountants.  Deloitte & Touche LLP, PricewaterhouseCoopers LLP
                -----------
and Arthur Andersen LLP, which have expressed their opinions with respect to the
financial statements for, respectively, Creative BioMolecules, Inc.
("Creative"), Ontogeny, Inc. ("Ontogeny") and Reprogenesis, Inc.
("Reprogenesis") (each of Creative, Ontogeny and Reprogenesis, a "Predecessor
Company" and, collectively, the "Predecessor Companies") contained in the Joint
Proxy Statement--Prospectus, are independent accountants as required by the
Securities Act and the rules and regulations promulgated thereunder.

          4.6.  No Defaults.  Except as disclosed in the Offering Materials, and
                -----------
except as to defaults, violations and breaches which individually or in the
aggregate would not have a Company Material Adverse Effect, the Company is not
in violation or default of any provision of its certificate of incorporation or
bylaws, or other organizational documents, or in breach of or default with
respect to any provision of any agreement, judgment, decree, order, mortgage,
deed of trust, lease, franchise, license, indenture, permit or other instrument
to which it is a party or by which it or any of its properties are bound; and
there does not exist any state of fact which, with notice or lapse of time or
both, would constitute an event of default on the part of the Company as defined
in such documents, except such defaults which individually or in the aggregate
would not have a Company Material Adverse Effect.

          4.7.  Contracts.  The contracts described in the Offering Materials
                ---------
are in full force and effect on the date hereof; and the Company is not, nor, to
the Company's knowledge, is any other party in breach of or default under any of
such contracts which would have a Company Material Adverse Effect.

          4.8.  No Actions.  Except as disclosed in the Offering Materials,
                ----------
there are no legal or governmental actions, suits or proceedings pending or, to
the Company's knowledge, threatened to which the Company is or may be a party or
of which property owned or leased by the Company is or may be the subject, or
related to environmental or discrimination matters, which actions, suits or
proceedings, individually or in the aggregate, might prevent or might reasonably
be expected to materially and adversely affect the transactions contemplated by
this Agreement or result in a Company Material Adverse Effect; and no labor
disturbance by the employees of the Company exists, to the Company's knowledge,
or is imminent which might reasonably be expected to have a Company Material
Adverse Effect.  Except as disclosed in the Offering Materials, the Company is
not a party to or subject to the provisions of any material injunction,
judgment, decree or order of any court, regulatory body administrative agency or
other governmental body.

          4.9.  Properties.   The Company has good and marketable title to all
                ----------
the properties and assets reflected as owned by them in the financial statements
included in the Offering

                                       4
<PAGE>

Materials, subject to no lien, mortgage, pledge, charge or encumbrance of any
kind except (i) those, if any, reflected in such financial statements, or (ii)
those which are not material in amount and do not adversely affect the use made
and promised to be made of such property by the Company. The Company holds its
leased properties under valid and binding leases, with such exceptions as are
not materially significant in relation to their respective businesses. Except as
disclosed in the Offering Materials, the Company owns or leases all such
properties as are necessary to its operations as now conducted.

          4.10.  No Material Change.  Since June 30, 2000 and except as
                 ------------------
specifically contemplated by the Offering Materials, (a) the Company has not
incurred any material liabilities or obligations, indirect, or contingent, or
entered into any material verbal or written agreement or other transaction which
is not in the ordinary course of business or which could reasonably be expected
to result in a material reduction in the future earnings of the Company; (b) the
Company has not sustained any material loss or interference with its businesses
or properties from fire, flood, windstorm, accident or other calamity not
covered by insurance; (c) the Company has not paid or declared any dividends or
other distributions with respect to its capital stock and the Company is not in
default in the payment of principal or interest on any outstanding debt
obligations; (d) there has not been any change in the capital stock of the
Company other than as contemplated by the Offering Materials and the sale of the
Shares hereunder or indebtedness material to the Company; and (e) there has not
occurred any event which has caused a Company Material Adverse Effect.

          4.11.  Intellectual Property.  Except as disclosed in or specifically
                 ---------------------
contemplated by the Offering Materials, (i) the Company owns or has obtained
valid and enforceable licenses or options for the inventions, patent
applications, patents, trademarks (both registered and unregistered),
tradenames, copyrights and trade secrets necessary for the conduct of the
Company's business as currently conducted and as the Offering Materials indicate
the Company contemplates conducting (collectively, the "Intellectual Property");
and (ii) to the Company's knowledge (for each of the following subsections (a)
through (e)):  (a) there are no third parties who have any ownership rights to
any Intellectual Property that is owned by, or has been licensed to, the Company
for the product indications described in the Offering Materials that would
preclude the Company from conducting its business as currently conducted and as
the Offering Materials indicate the Company contemplates conducting; (b) there
are currently no sales of any products that would constitute an infringement by
third parties of any Intellectual Property owned, licensed or optioned by the
Company; (c) there is no pending or threatened action, suit, proceeding or claim
by others challenging the rights of the Company in or to any Intellectual
Property owned, licensed or optioned by the Company, other than non-material
claims; (d) there is no pending or threatened action, suit, proceeding or claim
by others challenging the validity or scope of any Intellectual Property owned,
licensed or optioned by the Company, other than non-material claims; and (e)
there is no pending or threatened action, suit, proceeding or claim by others
that the Company infringes or otherwise violate any patent, trademark,
copyright, trade secret or other proprietary right of others, other than non-
material claims.

          4.12.  Compliance.  The Company has not been advised, and has no
                 ----------
reason to believe, that it is not conducting its business in compliance with all
applicable laws, rules and

                                       5
<PAGE>

regulations of the jurisdictions in which it is conducting business, including,
without limitation, all applicable local, state and federal environmental laws
and regulations; except where failure to be so in compliance would not have a
Company Material Adverse Effect.

          4.13.  Taxes.  The Company has filed all necessary federal, state and
                 -----
foreign income and franchise tax returns and has paid or accrued all taxes shown
as due thereon, and the Company has no knowledge of a tax deficiency which has
been or might be asserted or threatened against it which could have a Company
Material Adverse Effect.

          4.14.  Transfer Taxes.  On the Closing Date, all stock transfer or
                 --------------
other taxes (other than income taxes) which are required to be paid in
connection with the sale and transfer of the Shares to be sold to the Purchaser
hereunder will be, or will have been, fully paid or provided for by the Company
and all laws imposing such taxes will be or will have been fully complied with.

          4.15.  Investment Company.  The Company is not an "investment company"
                 ------------------
or an "affiliated person" of, or "promoter" or "principal underwriter" for an
investment company, within the meaning of the Investment Company Act of 1940, as
amended.

          4.16.  Offering Materials.  The Company has not distributed and will
                 ------------------
not distribute prior to the Closing Date any offering material in connection
with the offering and sale of the Shares other than the Offering Materials or
any amendment or supplement thereto.  The Company has not in the past nor will
it hereafter take any action independent of the Placement Agent to sell, offer
for sale or solicit offers to buy any securities of the Company which would
bring the offer, issuance or sale of the Shares, as contemplated by this
Agreement, within the provisions of Section 5 of the Securities Act, unless such
offer, issuance or sale was or shall be within the exemptions of Section 4 of
the Securities Act.

          4.17.  Insurance.  The Company maintains insurance of the type and in
                 ---------
the amount that the Company reasonably believes is adequate for its business,
including, but not limited to, insurance covering all real and personal property
owned or leased by the Company against theft, damage, destruction, acts of
vandalism and all other risks customarily insured against by similarly situated
companies, all of which insurance is in full force and effect.

          4.18.  Contributions.  At no time since its incorporation has the
                 -------------
Company, directly or indirectly, (a) made any unlawful contribution to any
candidate for public office, or failed to disclose fully any contribution in
violation of law, or (b) made any payment to any federal or state governmental
officer or official, or other person charged with similar public or quasi-public
duties, other than payments required or permitted by the laws of the United
States or any jurisdiction thereof.

          4.19.  Additional Information.   The Company represents and warrants
                 ----------------------
that the information contained in the following documents, which the Placement
Agent has furnished to the Purchaser, or will furnish prior to the Closing or in
connection with Section 7 hereof, is or will be true and correct in all material
respects as of their respective final dates:

          (a)    the Joint Proxy Statement--Prospectus;

                                       6
<PAGE>

          (b)    the Company's Quarterly Report on Form 10-Q for the fiscal
                 quarter ended June 30, 2000;

          (c)    the Company's Current Reports on Form 8-K and Form 8-K/A filed
                 with the Commission on August 10, 2000 and August 14, 2000,
                 respectively;

          (d)    the Registration Statement;

          (e)    the Offering Materials, including all addenda and exhibits
                 thereto (other than the Appendices);

          (f)    the Registration Statement on Form 8-A describing the Common
                 Stock; and

          (g)    all other documents, if any, filed by the Company with the
                 Commission since its incorporation pursuant to the reporting
                 requirements of the Securities Exchange Act of 1934, as amended
                 (the "Exchange Act").

          4.20.  Legal Opinions.  Prior to the Closing, (a) Hale & Dorr LLP,
                 --------------
counsel to the Company, will deliver its legal opinion to the Placement Agent
substantially in the form of Exhibit A hereto and (b) Foley, Hoag & Eliot LLP,
Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C. and Baker Botts LLP,
intellectual property counsel to the Company and formerly intellectual property
counsel to Ontogeny, Creative and Reprogenesis, respectively, will deliver legal
opinions to the Placement Agent substantially in the form of Exhibit B hereto,
in each case with such changes therein as such counsel rendering the opinion and
the Placement Agent may agree upon.  Each such opinion shall also state that
each of the Purchasers may rely thereon as though it were addressed directly to
such Purchaser.

          4.21.  Certificate.  At the Closing, the Company will deliver to
                 -----------
Purchaser a certificate executed by the Chairman of the Board or President and
the chief financial or accounting officer of the Company, dated the Closing
Date, in form and substance reasonably satisfactory to the Purchasers, to the
effect that the representations and warranties of the Company set forth in this
Section 4 are true and correct in all material respects as of the date of this
Agreement and as of the Closing Date, and the Company has complied with all the
agreements and satisfied all the conditions herein on its part to be performed
or satisfied on or prior to such Closing Date.

          4.22.  Price of Common Stock.  The Company has not taken, and will not
                 ---------------------
take, directly or indirectly, any action designed to cause or result in, or
which has constituted or which might reasonably be expected to constitute, the
stabilization or manipulation of the price of the shares of the Common Stock to
facilitate the sale or resale of the Common Stock.

          4.23.  Resale Registration Statement.  The Company agrees to deliver
                 -----------------------------
or to cause to be delivered to each Purchaser a draft of the proposed form of
Registration Statement prior to its initial filing with the Commission; provided
                                                                        --------
that each Purchaser shall agree prior to such

                                       7
<PAGE>

delivery to maintain in strict confidence and not disclose to any third party
any material nonpublic information contained in the Registration Statement and
shall neither purchase nor sell shares of the Common Stock from the date of
delivery until the Registration Statement is filed.

          SECTION 5.  Representations, Warranties and Covenants of the
                      ------------------------------------------------
Purchaser.  (a)  The Purchaser represents and warrants to, and covenants with,
---------
the Company that:  (i) the Purchaser is knowledgeable, sophisticated and
experienced in making, and is qualified to make, decisions with respect to
investments in shares representing an investment decision like that involved in
the purchase of the Shares, including investments in securities issued by the
Company, and has requested, received, reviewed and considered all information it
deems relevant in making an informed decision to purchase the Shares; (ii) the
Purchaser is acquiring the number of Shares set forth in Section 2 above in the
ordinary course of its business and for its own account for investment (as
defined for purposes of the Hart-Scott-Rodino Antitrust Improvement Act of 1976
and the regulations thereunder) only and with no present intention of
distributing any of such Shares or any arrangement or understanding with any
other persons regarding the distribution of such Shares within the meaning of
Section 2(11) of the Securities Act; (iii) the Purchaser will not, directly or
indirectly, offer, sell, pledge, transfer or otherwise dispose of (or solicit
any offers to buy, purchase or otherwise acquire or take a pledge of) any of the
Shares except in compliance with the Securities Act and the Rules and
Regulations; (iv) the Purchaser has completed or caused to be completed the
Registration Statement Questionnaire and the Stock Certificate Questionnaire,
both attached hereto as Appendix I, for use in preparation of the Registration
Statement, and the answers thereto are true and correct as of the date hereof
and will be true and correct as of the effective date of the Registration
Statement; (v) the Purchaser has, in connection with its decision to purchase
the number of Shares set forth in Section 2 above, relied solely upon the
Offering Materials and the representations and warranties of the Company
contained herein; and (vi) the Purchaser is an "accredited investor" within the
meaning of Rule 501 of Regulation D promulgated under the Securities Act.

          (b)  The Purchaser hereby covenants with the Company not to make any
sale of the Shares without satisfying the prospectus delivery requirement under
the Securities Act, and the Purchaser acknowledges and agrees that such Shares
are not transferable on the books of the Company unless the certificate
submitted to the transfer agent evidencing the Shares is accompanied by a
separate officer's certificate:  (i) in the form of Appendix II hereto, (ii)
executed by an officer of, or other authorized person designated by, the
Purchaser, and (iii) to the effect that (A) the Shares have been sold in
accordance with the Registration Statement, the Securities Act and the Rules and
Regulations and any applicable state securities or blue sky laws and (B) the
requirement of delivering a current prospectus has been satisfied.  The
Purchaser acknowledges that there may occasionally be times when the Company has
the right to suspend the use of the prospectus forming a part of the
Registration Statement in accordance with Section 7.2 below.  The Purchaser
hereby covenants that it will not sell any Shares pursuant to said prospectus
during the period commencing at the time at which the Company gives the
Purchaser written notice of the suspension of the use of said prospectus and
ending at the time the Company gives the Purchaser written notice that the
Purchaser may thereafter effect sales pursuant to said prospectus.  The
Purchaser further covenants to notify the Company promptly of the sale of all of
its Shares.

                                       8
<PAGE>

          (c)  The Purchaser further represents and warrants to, and covenants
with, the Company that (i) the Purchaser has full right, power, authority and
capacity to enter into this Agreement and to consummate the transactions
contemplated hereby and has taken all necessary action to authorize the
execution, delivery and performance of this Agreement, and (ii) upon the
execution and delivery of this Agreement, this Agreement shall constitute a
valid and binding obligation of the Purchaser enforceable in accordance with its
terms, except as enforceability may be limited by applicable bankruptcy,
insolvency, reorganization, moratorium or similar laws affecting creditors' and
contracting parties' rights generally and except as enforceability may be
subject to general principles of equity (regardless of whether such
enforceability is considered in a proceeding in equity or at law) and except as
the indemnification agreements of the Purchaser in Section 7.4 hereof may be
legally unenforceable.

          SECTION 6.  Survival of Representations, Warranties and Agreements.
                      ------------------------------------------------------
Notwithstanding any investigation made by any party to this Agreement or by the
Placement Agent, all covenants, agreements, representations and warranties made
by the Company and the Purchaser herein and in the certificates for the Shares
delivered pursuant hereto shall survive the execution of this Agreement, the
delivery to the Purchaser of the Shares being purchased and the payment
therefor.

          SECTION 7.  Registration of the Shares; Compliance with the Securities
                      ----------------------------------------------------------
Act.
---

          7.1. Registration Procedures and Expenses.  The Company shall:
               ------------------------------------

          (a)  as soon as practicable, prepare and file with the Commission the
               Registration Statement on Form S-1 relating to the sale of the
               Shares by the Purchaser from time to time through the automated
               quotation system of the Nasdaq National Market or the facilities
               of any national securities exchange on which the Company's Common
               Stock is then traded or in privately-negotiated transactions;

          (b)  use its reasonable efforts, subject to the receipt of necessary
               information from the Purchasers, to cause the Commission to
               notify the Company of the Commission's willingness to declare the
               Registration Statement effective as soon as practicable, but in
               any event within 75 days after the date the Registration
               Statement is filed by the Company;

          (c)  prepare and file with the Commission such amendments and
               supplements to the Registration Statement and the prospectus used
               in connection therewith as may be necessary to keep the
               Registration Statement effective until the earlier of (i) twenty-
               four months after the effective date of the Registration
               Statement or (ii) the date on which the Shares may be resold by
               the Purchasers without registration by reason of Rule 144(k)
               under the Securities Act or any other rule of similar effect;

          (d)  as soon as practicable after the Registration Statement becomes
               effective, prepare, and within 30 business days after the Company
               becomes eligible

                                       9
<PAGE>

               to file registration statements on Form S-3 in accordance with
               the General Instructions regarding the use of Form S-3, file with
               the Commission, such amendments and supplements to the
               Registration Statement and the prospectus used in connection
               therewith as may be necessary to convert the Registration
               Statement from a registration statement on Form S-1 to a
               registration statement on Form S-3;

          (e)  furnish to the Purchaser with respect to the Shares registered
               under the Registration Statement (and to each underwriter, if
               any, of such Shares) such reasonable number of copies of
               prospectuses in order to facilitate the public sale or other
               disposition of all or any of the Shares by the Purchaser;

               provided, however, that the obligation of the Company to deliver
               --------  -------
               copies of prospectuses to the Purchaser shall be subject to the
               receipt by the Company of reasonable assurances from the
               Purchaser that the Purchaser will comply with the applicable
               provisions of the Securities Act and of such other securities or
               blue sky laws as may be applicable in connection with any use of
               such prospectuses;

          (f)  file documents required of the Company for normal blue sky
               clearance in states specified in writing by the Purchaser;
               provided, however, that the Company shall not be required to
               --------  -------
               qualify to do business or consent to service of process in any
               jurisdiction in which it is not now so qualified or has not so
               consented; and

          (g)  bear all expenses in connection with the procedures in paragraphs
               (a) through (f) of this Section 7.1 and the registration of the
               Shares pursuant to the Registration Statement, other than fees
               and expenses, if any, of counsel or other advisers to the
               Purchaser or the Other Purchasers or underwriting discounts,
               brokerage fees and commissions incurred by the Purchaser or the
               Other Purchasers, if any.

          7.2. Material Events.  Notwithstanding anything in this Agreement to
               ---------------
the contrary, if the Company shall furnish to the Purchaser a certificate signed
by the President or Chief Executive Officer of the Company stating that the
Board of Directors of the Company has made the good faith determination (i) that
continued use by the Purchaser of the Registration Statement for purposes of
effecting offers or sales of Shares pursuant thereto would require, under the
Securities Act, premature disclosure in the Registration Statement (or the
prospectus relating thereto) of material, nonpublic information concerning the
Company or its business, (ii) that such premature disclosure would be materially
adverse to the Company or its business, and (iii) that it is therefore desirable
to suspend the use by the Purchaser of such Registration Statement (and the
prospectus relating thereto) for purposes of effecting offers or sales of Shares
pursuant thereto, then the right of the Purchaser to use the Registration
Statement (and the prospectus relating hereto) for purposes of effecting offers
and sales of Shares pursuant thereto shall be suspended.  Notwithstanding the
foregoing, the aggregate number of days in any such twelve (12) month period
during which the use of the Registration Statement may be suspended pursuant to
this Section 7.2 shall not exceed sixty (60) days.  The Purchaser hereby
covenants

                                      10
<PAGE>

and agrees that it will not sell any Shares pursuant to the Registration
Statement during the periods the Registration Statement is withdrawn or the
ability to sell thereunder is suspended as set forth in this Section 7.2.

          7.3.  Transfer of Shares After Registration.  The Purchaser agrees
                -------------------------------------
that it will not effect any disposition of the Shares or its right to purchase
the Shares that would constitute a sale within the meaning of the Securities
Act, except as contemplated in the Registration Statement referred to in Section
7.1 or as otherwise permitted by law, and that it will promptly notify the
Company of any changes in the information set forth in the Registration
Statement regarding the Purchaser or its Plan of Distribution.

          7.4.  Indemnification. For the purpose of this Section 7.4:
                ---------------

          (i)    the term "Purchaser/Affiliate" shall mean any affiliate of the
                 Purchaser and any person who controls the Purchaser or any
                 affiliate of the Purchaser within the meaning of Section 15 of
                 the Securities Act or Section 20 of the Exchange Act; and

          (ii)   the term "Registration Statement" shall include any final
                 prospectus, exhibit, supplement or amendment included in or
                 relating to the Registration Statement referred to in Section
                 7.1.

          (a)    The Company agrees to indemnify and hold harmless each
Purchaser and each Purchaser/Affiliate against any losses, claims, damages,
liabilities or expenses, joint or several, to which such Purchaser or
Purchaser/Affiliate may become subject, under the Securities Act, the Exchange
Act, or any other federal or state statutory law or regulation, or at common law
or otherwise (including in settlement of any litigation, if such settlement is
effected with the written consent of the Company), insofar as such losses,
claims, damages, liabilities or expenses (or actions in respect thereof as
contemplated below) arise out of or are based upon any untrue statement or
alleged untrue statement of any material fact contained in the Registration
Statement, including the prospectus, financial statements and schedules, and all
other documents filed as a part thereof, as amended at the time of effectiveness
of the Registration Statement, including any information deemed to be a part
thereof as of the time of effectiveness pursuant to paragraph (b) of Rule 430A,
or pursuant to Rule 434, of the Rules and Regulations, or the prospectus, in the
form first filed with the Commission pursuant to Rule 424(b) of the Regulations,
or filed as part of the Registration Statement at the time of effectiveness if
no Rule 424(b) filing is required (the "Prospectus"), or any amendment or
supplement thereto, or arise out of or are based upon the omission or alleged
omission to state in any of them a material fact required to be stated therein
or necessary to make the statements in any of them, in light of the
circumstances under which they were made, not misleading, or arise out of or are
based in whole or in part on any inaccuracy in the representations and
warranties of the Company contained in this Agreement, or any failure of the
Company to perform its obligations hereunder or under law, and will reimburse
each such Purchaser and each such Purchaser/Affiliate for any legal and other
expenses as such expenses are reasonably incurred by such Purchaser or such
Purchaser/Affiliate in connection with investigating, defending, settling,
compromising or paying any such loss, claim, damage, liability, expense or
action; provided, however, that the Company will not be
        --------  -------

                                       11
<PAGE>

liable in any such case to the extent that any such loss, claim, damage,
liability or expense arises out of or is based upon (i) an untrue statement or
alleged untrue statement or omission or alleged omission made in the
Registration Statement, the Prospectus or any amendment or supplement thereto in
reliance upon and in conformity with written information furnished to the
Company by or on behalf of the Purchaser expressly for use therein, or (ii) the
failure of such Purchaser to comply with the covenants and agreements contained
in Sections 5(b) or 7.3 hereof respecting sale of the Shares, or (iii) the
inaccuracy of any representations made by such Purchaser herein or (iv) any
statement or omission in any Prospectus that is corrected in any subsequent
Prospectus that was delivered to the Purchaser prior to the pertinent sale or
sales by the Purchaser.

          (b) Each Purchaser will severally indemnify and hold harmless the
Company, each of its directors, each of its officers who signed the Registration
Statement and each person, if any, who controls the Company within the meaning
of the Securities Act, against any losses, claims, damages, liabilities or
expenses to which the Company, each of its directors, each of its officers who
signed the Registration Statement or controlling person may become subject,
under the Securities Act, the Exchange Act, or any other federal or state
statutory law or regulation, or at common law or otherwise (including in
settlement of any litigation, if such settlement is effected with the written
consent of such Purchaser) insofar as such losses, claims, damages, liabilities
or expenses (or actions in respect thereof as contemplated below) arise out of
or are based upon (i) any failure to comply with the covenants and agreements
contained in Sections 5(b) or 7.3 hereof respecting the sale of the Shares or
(ii) the inaccuracy of any representation made by such Purchaser herein or (iii)
any untrue or alleged untrue statement of any material fact contained in the
Registration Statement, the Prospectus, or any amendment or supplement thereto,
or arise out of or are based upon the omission or alleged omission to state
therein a material fact required to be stated therein or necessary to make the
statements therein not misleading, in each case to the extent, but only to the
extent, that such untrue statement or alleged untrue statement or omission or
alleged omission was made in the Registration Statement, the Prospectus, or any
amendment or supplement thereto, in reliance upon and in conformity with written
information furnished to the Company by or on behalf of any Purchaser expressly
for use therein, and will reimburse the Company, each of its directors, each of
its officers who signed the Registration Statement or controlling person for any
legal and other expense reasonably incurred by the Company, each of its
directors, each of its officers who signed the Registration Statement or
controlling person in connection with investigating, defending, settling,
compromising or paying any such loss, claim, damage, liability, expense or
action.

          (c) Promptly after receipt by an indemnified party under this Section
7.4 of notice of the threat or commencement of any action, such indemnified
party will, if a claim in respect thereof is to be made against an indemnifying
party under this Section 7.4 promptly notify the indemnifying party in writing
thereof; but the omission so to notify the indemnifying party will not relieve
it from any liability which it may have to any indemnified party for
contribution or otherwise than under the indemnity agreement contained in this
Section 7.4 or to the extent it is not prejudiced as a result of such failure.
In case any such action is brought against any indemnified party and such
indemnified party seeks or intends to seek indemnity from an indemnifying party,
the indemnifying party will be entitled to participate in, and, to the extent
that it may wish, jointly with all other indemnifying parties similarly
notified, to assume

                                       12
<PAGE>

the defense thereof with counsel reasonably satisfactory to such indemnified
party; provided, however, if the defendants in any such action include both the
indemnified party and the indemnifying party and the indemnified party shall
have reasonably concluded that there may be a conflict between the positions of
the indemnifying party and the indemnified party in conducting the defense of
any such action or that there may be legal defenses available to it and/or other
indemnified parties which are different from or additional to those available to
the indemnifying party, the indemnified party or parties shall have the right to
select separate counsel to assume such legal defenses and to otherwise
participate in the defense of such action on behalf of such indemnified party or
parties. Upon receipt of notice from the indemnifying party to such indemnified
party of its election so to assume the defense of such action and approval by
the indemnified party of counsel, the indemnifying party will not be liable to
such indemnified party under this Section 7.4 for any legal or other expenses
subsequently incurred by such indemnified party in connection with the defense
thereof unless (i) the indemnified party shall have employed such counsel in
connection with the assumption of legal defenses in accordance with the proviso
to the preceding sentence (it being understood, however, that the indemnifying
party shall not be liable for the expenses of more than one separate counsel,
approved by such indemnifying party, representing all of the indemnified parties
who are parties to such action) or (ii) the indemnifying party shall not have
employed counsel reasonably satisfactory to the indemnified party to represent
the indemnified party within a reasonable time after notice of commencement of
action, in each of which cases the reasonable fees and expenses of counsel shall
be at the expense of the indemnifying party.

          (d) If the indemnification provided for in this Section 7.4 is
required by its terms but is for any reason held to be unavailable to or
otherwise insufficient to hold harmless an indemnified party under paragraphs
(a), (b) or (c) of this Section 7.4 in respect to any losses, claims, damages,
liabilities or expenses referred to herein, then each applicable indemnifying
party shall contribute to the amount paid or payable by such indemnified party
as a result of any losses, claims, damages, liabilities or expenses referred to
herein (i) in such proportion as is appropriate to reflect the relative benefits
received by the Company and the Purchaser from the placement of Common Stock or
(ii) if the allocation provided by clause (i) above is not permitted by
applicable law, in such proportion as is appropriate to reflect not only the
relative benefits referred to in clause (i) above but the relative fault of the
Company and the Purchaser in connection with the statements or omissions or
inaccuracies in the representations and warranties in this Agreement which
resulted in such losses, claims, damages, liabilities or expenses, as well as
any other relevant equitable considerations. The respective relative benefits
received by the Company on the one hand and each Purchaser on the other shall be
deemed to be in the same proportion as the amount paid by such Purchaser to the
Company pursuant to this Agreement for the Shares purchased by such Purchaser
that were sold pursuant to the Registration Statement bears to the difference
(the "Difference") between the amount such Purchaser paid for the Shares that
were sold pursuant to the Registration Statement and the amount received by such
Purchaser from such sale. The relative fault of such Selling Stockholders and
each Purchaser shall be determined by reference to, among other things, whether
the untrue or alleged statement of a material fact or the omission or alleged
omission to state a material fact or the inaccurate or the alleged inaccurate
representation and/or warranty relates to information supplied by the Company or
by such Purchaser and the parties' relative intent, knowledge, access to
information and opportunity to correct or prevent such statement or omission.
The amount paid or payable

                                       13
<PAGE>

by a party as a result of the losses, claims, damages, liabilities and expenses
referred to above shall be deemed to include, subject to the limitations set
forth in paragraph (c) of this Section 7.4, any legal or other fees or expenses
reasonably incurred by such party in connection with investigating or defending
any action or claim. The provisions set forth in paragraph (c) of this Section
7.4 with respect to the notice of the threat or commencement of any threat or
action shall apply if a claim for contribution is to be made under this
paragraph (d); provided, however, that no additional notice shall be required
               --------  -------
with respect to any threat or action for which notice has been given under
paragraph (c) for purposes of indemnification. The Company and each Purchaser
agree that it would not be just and equitable if contribution pursuant to this
Section 7.4 were determined solely by pro rata allocation (even if the Purchaser
were treated as one entity for such purpose) or by any other method of
allocation which does not take account of the equitable considerations referred
to in this paragraph. Notwithstanding the provisions of this Section 7.4, no
Purchaser shall be required to contribute any amount in excess of the amount by
which the Difference exceeds the amount of any damages that such Purchaser has
otherwise been required to pay by reason of such untrue or alleged untrue
statement or omission or alleged omission. No person guilty of fraudulent
misrepresentation (within the meaning of Section 11(f) of the Securities Act)
shall be entitled to contribution from any person who was not guilty of such
fraudulent misrepresentation. The Purchasers' obligations to contribute pursuant
to this Section 7.4 are several and not joint.

          7.5.  Termination of Conditions and Obligations.  The restrictions
                -----------------------------------------
imposed by Section 5 or this Section 7 upon the transferability of the Shares
shall cease and terminate as to any particular number of the Shares upon the
passage of twenty-four months from the effective date of the Registration
Statement covering such Shares or at such time as an opinion of counsel
satisfactory in form and substance to the Company shall have been rendered to
the effect that such conditions are not necessary in order to comply with the
Securities Act.

          7.6.  Information Available.  So long as the Registration Statement is
                ---------------------
effective covering the resale of Shares owned by the Purchaser, the Company will
furnish to the Purchaser:

          (a)   as soon as practicable after available (but in the case of the
                Company's Annual Report to Stockholders, within 120 days after
                the end of each fiscal year of the Company), one copy of (i) its
                Annual Report to Stockholders (which Annual Report shall contain
                financial statements audited in accordance with generally
                accepted accounting principles by a national firm of certified
                public accountants), (ii) if not included in substance in the
                Annual Report to Stockholders, its Annual Report on Form 10-K,
                (iii) its Quarterly Reports to Stockholders, if any, (iv) if not
                included in substance in its Quarterly Reports to Stockholders,
                its quarterly reports on Form 10-Q, and (v) a full copy of the
                particular Registration Statement covering the Shares (the
                foregoing, in each case, excluding exhibits);

                                       14
<PAGE>

          (b)   upon the reasonable request of the Purchaser, a reasonable
                number of copies of the prospectuses, and any supplements
                thereto, to supply to any other party requiring such
                prospectuses;

and the Company, upon the reasonable request of the Purchaser, will meet with
the Purchaser or a representative thereof at the Company's headquarters to
discuss information relevant for disclosure in the Registration Statement
covering the Shares and will otherwise cooperate with any Purchaser conducting
an investigation for the purpose of reducing or eliminating such Purchaser's
exposure to liability under the Securities Act, including the reasonable
production of information at the Company's headquarters, subject to appropriate
confidentiality limitations.

          SECTION 8.  Broker's Fee.  The Purchaser acknowledges that the Company
                      ------------
intends to pay to the Placement Agent a fee in respect of the sale of the Shares
to the Purchaser.  Each of the parties hereto hereby represents that, on the
basis of any actions and agreements by it, there are no other brokers or finders
entitled to compensation in connection with the sale of the Shares to the
Purchaser.

          SECTION 9.  Notices.  All notices, requests, consents and other
                      -------
communications hereunder shall be in writing, shall be mailed by first-class
registered or certified airmail, confirmed facsimile or nationally recognized
overnight express courier postage prepaid, and shall be deemed given when so
mailed and shall be delivered as addressed as follows:

          (a)  if to the Company, to:

                    Curis, Inc.
                    61 Moulton Street
                    Cambridge, Massachusetts 02138
                    Telecopier:  (617) 876-0866
                    Attn:  General Counsel

               with a copy to:

                    Hale and Dorr LLP
                    60 State Street
                    Boston, MA 02109
                    Telecopier:  (617) 526-5000
                    Attn:   Steven D. Singer, Esq.

               or to such other person at such other place as the Company shall
               designate to the Purchaser in writing; and

          (b)  if to the Purchaser, at its address as set forth at the end of
               this Agreement, or at such other address or addresses as may have
               been furnished to the Company in writing.

                                       15
<PAGE>

          SECTION 10.  Changes.  This Agreement may not be modified or amended
                       -------
except pursuant to an instrument in writing signed by the Company and the
Purchaser.

          SECTION 11.  Headings.  The headings of the various sections of this
                       --------
Agreement have been inserted for convenience of reference only and shall not be
deemed to be part of this Agreement.

          SECTION 12.  Severability.  In case any provision contained in this
                       ------------
Agreement should be invalid, illegal or unenforceable in any respect, the
validity, legality and enforceability of the remaining provisions contained
herein shall not in any way be affected or impaired thereby.

          SECTION 13.  Governing Law.  This Agreement shall be governed by and
                       -------------
construed in accordance with the laws of the State of New York and the federal
law of the United States of America.

          SECTION 14.  Counterparts.  This Agreement may be executed in two or
                       ------------
more counterparts, each of which shall constitute an original, but all of which,
when taken together, shall constitute but one instrument, and shall become
effective when one or more counterparts have been signed by each party hereto
and delivered to the other parties.

          SECTION 15.  Entire Agreement. This Agreement and the instruments
                       ----------------
referenced herein contain the entire understanding of the parties with respect
to the matters covered herein and therein and, except as specifically set forth
herein or therein, neither the Company nor the Purchaser makes any
representation, warranty, covenant or undertaking with respect to such matters.

                                       16
<PAGE>

                                                                     Exhibit 10.
                                                                     ----------
                                                                             --

          IN WITNESS WHEREOF, the parties hereto have caused this Agreement to
be executed by their duly authorized representatives as of the day and year
first above written.

                              CURIS, INC.

                              By    _________________________________

Print or Type:
                              Name of Purchaser
                               (Individual or Institution):

                                    _________________________________

                              Name of Individual representing
                               Purchaser (if an Institution):

                                    _________________________________

                              Title of Individual representing
                               Purchaser (if an Institution):

                                    _________________________________

Signature by:
                              Individual Purchaser or Individual
                                representing Purchaser:

                                    _________________________________

                              Address:    ___________________________

                              Telephone:  ___________________________

                              Telecopier: ___________________________

                                       17
<PAGE>

                    SUMMARY INSTRUCTION SHEET FOR PURCHASER
                    ---------------------------------------

                  (to be read in conjunction with the entire
                       Purchase Agreement which follows)

A.   Complete the following items on the Purchase Agreement:

     1.   Page 15 - Signature:

          (i)     Name of Purchaser (Individual or Institution)

          (ii)    Name of Individual representing Purchaser (if an Institution)

          (iii)   Title of Individual representing Purchaser (if an Institution)

          (iv)    Signature of Individual Purchaser or Individual representing
                  Purchaser

     2.           Appendix I - Registration Statement Questionnaire:

                  Provide the information requested by the Registration
                  Statement Questionnaire.

                  Appendix II - Stock Certificate Questionnaire:

                  Provide the information requested by the Stock Certificate
                  Questionnaire.

     3.           Return the properly completed and signed Purchase Agreement
                  including the properly completed Appendix I for each account
                  purchasing Shares to:

                  Prudential Vector Healthcare Group
                  1751 Lake Cook Road, Suite 350
                  Deerfield, IL 60015
                  Attention: Mr. Bernard Hoffmann

B.   Instructions regarding the transfer of funds for the purchase of Shares
     will be sent by facsimile to the Purchaser by the Placement Agent at a
     later date.

C.   Upon the resale of the Shares by the Purchaser after the Registration
     Statement covering the Shares is effective, as described in the Purchase
     Agreement, the Purchaser:

                  (i)  must deliver a current prospectus of the Company to the
                       buyer (prospectuses must be obtained from the Company at
                       the Purchaser's request); and

                  (ii) must send a letter in the form of Appendix II to the
                       Company so that the Shares may be properly transferred.

                                       18
<PAGE>

                                                              Appendix I
                                                             (one of two)

                                  CURIS, INC.

                        STOCK CERTIFICATE QUESTIONNAIRE
                        -------------------------------

     Pursuant to Section 3 of the Agreement, please provide us with the
following information:

1.   The exact name that your Shares are to be registered in (this is the name
     that will appear on your stock certificate(s)).  You may use a nominee name
     if appropriate:

     __________________________________________

2.   The relationship between the Purchaser of the Shares and the Registered
     Holder listed in response to item 1 above:

     __________________________________________

3.   The mailing address of the Registered Holder listed in response to item 1
     above:

     __________________________________________

     __________________________________________

     __________________________________________

     __________________________________________

4.   The Social Security Number or Tax Identification Number of the Registered
     Holder listed in response to item 1 above:

     __________________________________________

                                       19
<PAGE>

                                                               Appendix I
                                                              (two of two)

                                  CURIS, INC.
                      REGISTRATION STATEMENT QUESTIONNAIRE
                      ------------------------------------

          In connection with the preparation of the Registration Statement,
please provide us with the following information:

          1.   Pursuant to the "Selling Shareholder" section of the Registration
Statement, please state your or your account's name exactly as it should appear
in the Registration Statement:

          ________________________________

          2.   Please provide the number of shares that you or your account will
own immediately after Closing, including those Shares purchased by you or your
account pursuant to this Purchase Agreement and those shares currently held by
you or your account that were acquired through other transactions:

          ________________________________

          3.   Have you or your organization had any position, office or other
material relationship within the past three years with the Company or its
affiliates?

               _____ Yes         _____ No

          If yes, please indicate the nature of any such relationships below:

              _________________________________________________________________

              _________________________________________________________________

              _________________________________________________________________

                                       20
<PAGE>

                                                                     APPENDIX II

Attention:

                  PURCHASER'S CERTIFICATE OF SUBSEQUENT SALE
                  ------------------------------------------

     The undersigned, [an officer of, or other person duly authorized by]

_________________________________________________________________________
             [fill in official name of individual or institution]

hereby certifies that he/she [said institution] is the Purchaser of the shares
evidenced by the attached certificate, and as such, sold such shares on
__________________ in accordance with Registration Statement number
      [date]

Registration Statement number __________________________________________________
                              [fill in the number of or otherwise identify the
                              Registration Statement]

and the requirement of delivering a current prospectus by the Company has been
complied with in connection with such sale.

Print or Type:

     Name of Purchaser
      (Individual or Institution):            _____________________________

     Name of Individual representing
      Purchaser (if an Institution):
                                              _____________________________

     Title of Individual representing
      Purchaser (if an Institution):          _____________________________

Signature by:

     Individual Purchaser or
      Individual representing Purchaser:      _____________________________
<PAGE>

                                                                       EXHIBIT A

                                FORM OF OPINION
                              OF HALE & DORR LLP

      1.  The Company is a corporation duly organized, validly existing and in
good standing under the laws of the State of Delaware. The Company is qualified
to do business as a foreign corporation in good standing in the Commonwealth of
Massachusetts which, to our knowledge, is the only jurisdiction in which it owns
or leases real property. The Company has all authority to own, lease, license
and operate its properties and assets and to conduct its business as described
in the Private Placement Memorandum.

      2.  The Company's authorized capital stock as of ____________, 2000 is as
set forth in the Private Placement Memorandum under the heading
"Capitalization;" there have been no changes in the authorized capital stock of
the Company since that date. The authorized capital stock of the Company
conforms in all material respects as to legal matters to the description thereof
incorporated by reference into the Private Placement Memorandum.

      3.  All of the outstanding shares of capital stock of the Company have
been duly authorized and validly issued and are fully paid and nonassessable and
were not issued in violation of or subject to any statutory preemptive or, to
our knowledge, similar contractual rights.

      4.  The Shares have been duly authorized and, when issued and delivered to
the Investors against payment therefor in accordance with the terms of the
Agreements, will be validly issued, fully paid and nonassessable and free of any
statutory preemptive or, to our knowledge, similar contractual rights.

      5.  The form of the certificates for the Shares conforms to the
requirements of Delaware General Corporation Law.

      6.  The Company has full corporate power and authority to enter into the
Agreements and the Engagement Letter and to issue, sell and deliver the Shares
to the Investors as provided in the Agreements, and the Agreements have been
duly authorized, executed and delivered by the Company and the Agreements are
the legal, valid and binding obligations of the Company, enforceable against the
Company in accordance with their terms, subject to customary exceptions for
bankruptcy and equitable remedies and indemnification/contribution provisions.

      7.  The Company's execution, delivery and performance of the Agreements
and the Engagement Letter do not and will not (i) violate the Certificate of
Incorporation or Bylaws of the Company, (ii) violate, result in a breach of or
constitute a default under (alone or with notice or passage of time or both) or
result in the creation or imposition of any lien, charge, claim, security
interest or encumbrance upon any property or assets of the Company under any
agreement, indenture, lease or other instrument to which the Company is a party
or by which it or any of its properties or assets is bound or subject that is
made an exhibit to the Company's Form S-4 or any Current Report on Form 8-K
filed by the Company subsequent to the filing of the
<PAGE>

Form S-4, or (iii) result in any violation by the Company of any existing
federal or Delaware corporate law, regulation or ruling which in our experience
is normally reviewed in transactions of the type contemplated by the Agreements
(assuming compliance with all applicable state securities and blue sky laws, the
Securities Act of 1933, as amended (the "Securities Act"), and the Securities
Exchange Act of 1934, as amended), or any judgment, injunction, order or decree
specifically naming the Company and known to us.

      8.  No consent, approval, authorization or order of, or registration or
filing with any federal or Delaware corporate governmental authority is required
on the part of the Company for the performance by the Company of its obligations
at the closing of the transactions contemplated by the Agreements, except as may
be required under the Securities Act or such as may be required under the state
securities or blue sky laws in connection with the purchase and sale of the
Shares.

      9.  To our knowledge, there are no actions, suits, arbitrations, claims,
governmental or other proceedings or investigations pending or threatened
against the Company or any of its operations, businesses, properties or assets
or which challenge the validity of any actions taken or to be taken by the
Company pursuant to the Agreements, the Engagement Letter or the transactions
contemplated thereby.

      10. To our knowledge, no holders of securities of the Company have rights,
which have not been waived or complied with, to the registration of shares of
Common Stock or other securities of the Company because of the filing of the
Resale Registration Statement or the offering contemplated thereby.

      11. The offer, issuance and sale of the Shares pursuant to the Private
Placement Memorandum and as contemplated under the terms of the Agreements are
not subject to the registration requirements of the Securities Act.
<PAGE>

                                                                   Exhibit 10.48
                                                                   -------------

                                                                       EXHIBIT B

                     Form of Intellectual Property Opinion

Prudential Vector Healthcare Group,
a unit of Prudential Securities Incorporated
1751 Lake Cook Road
Deerfield, IL 60015

Each of the Purchasers named on Schedule A hereto

      Re:  [Name of Company]
           -----------------

Ladies and Gentlemen:

      This letter is being furnished to you at the request of Curis, Inc.
(herein the "Company") pursuant to Section 4.11 of the Purchase Agreements dated
_________, 2000 between you and the Company, relating to the issuance and sale
to you of certain shares of common stock of the Company.

      Curis, Inc. is a company that was formed by the merger of Creative
BioMolecules, Inc., Ontogeny, Inc. and Reprogenesis, Inc. From time to time, we
serve as patent counsel for the Company and, prior to the merger, for
[predecessor company client] for certain of its patents and patent applications
(herein "Intellectual Property"). We are familiar with certain of the technology
used by the Company in its business, to the extent of its disclosure to us by
the Company, which is the subject matter of certain of the [predecessor company
client] Origin Intellectual Property described in the Registration Statement. We
have reviewed those sections of the Registration Statement on Form S-4 (File No.
_________) (the "Registration Statement") and TITLED "[whatever the relevant
heading names are]". We are generally familiar with certain [predecessor company
client] Origin aspects of the Company's business and have reviewed the
description thereof in the Registration Statement. The opinions and beliefs
expressed in this letter represent our considered judgment and are based upon
compilations of applicable laws generally available to the public and effective
as of the date hereof.

      As used in this letter, the phrase "to our knowledge" when used as a
qualification with respect to the existence or absence of any matter, means
that, during our representation of the Company and having no independent
investigation with respect thereto, no information has come to our attention
which has given us actual knowledge of the existence of facts contrary to the
stated existence or absence of the matter.

      Based on our review of the above-identified sections of the Registration
Statement, and subject to and limited by the foregoing and the exceptions and
limitations set forth below, we offer the following opinions and conclusions:
<PAGE>

1.  Except as set forth below, to our knowledge, with respect to the statements
in the above identified sections in the Registration Statement, insofar as such
statements pertain to [predecessor company client] Origin patent matters,
nothing has come to our attention that would form a basis for a belief, as of
the even date herewith, that said sections contain any untrue statement of a
material fact, or omit to state any materials fact necessary to make the
statements accurately and fairly represent the information referred to therein.
We express no opinion, however, as to the bases upon which the Company decides
to file patent applications, the dependency of the Company's commercial success
on any factors including protection of proprietary technology and the
procurement and enforceability of patents, nor as to the Company's reliance on
various methods to protect its proprietary rights.

2.  With respect to those patent applications which we have prosecuted on behalf
of the Company or its predecessor, to our knowledge, and based upon a
representation by the Company, the inventors, and, as applicable, any licensor,
regarding the conception and reduction to practice of the patents and patent
applications directed to the [predecessor company client] Origin technology
described in the Registration Statement, and noting that we have not been
directed by the Company to undertake an investigation or analysis in this
regard, nor have we undertaken such investigation or analysis, we are not aware
of any rights of parties, other than the Company's or licensor's, or the U.S.
government under 35 USC (S)200-12, to any of the [predecessor company client]
Origin patents or patent applications directed to the technology described in
the Registration Statement, and other than as disclosed in the Registration
Statement, we are not aware of any pending or threatened actions, suits,
proceedings or claims by others challenging the Company's rights to or in any
such patents, patent applications or trade secret rights and we are not aware of
any pending or threatened actions, suits, proceedings or claims by others that
the Company is infringing or otherwise violating any patent or trade secret
rights of others.

3.  We note that we have assumed responsibility for several of patent filings
licensed to, or owned by, the Company from other law firms which prepared and
filed the applications, and some instance, undertook substantial prosecution of
the applications before the United States Patent and Trademark Office;
consequently, we are not in a position to opine to the completeness of their
disclosure.  We are only familiar with those patent applications which we have
prosecuted on behalf of the Company or its predecessor, and with respect to
those applications, have not been made aware of any facts or opinions which have
led us to form the belief that any such patent applications would be
unenforceable or invalid if issued as patents with claims of reasonable scope.

4.  While we have not been asked by the Company to review any license agreements
or other contracts, nor have we undertaken such review, we are not aware of any
agreements with third parties relating to the acquisition, licensing and/or
transfer of intellectual property rights which have or are anticipated to have a
material impact on the Company's existing or future business, including license
agreements, joint venture agreements, marketing and/or distribution agreements
or other collaboration agreements, that are not currently in effect or that will
be expiring soon, nor further are we aware that there has been any notice of
termination or other act indicating a desire to terminate any of the aforesaid
agreements.
<PAGE>

     In rendering this opinion, no patent search or validity or enforceability
study has been undertaken with respect to any of the Company's filed patent
applications, nor have we undertaken any infringement or right-to-use
investigations with respect to the rights of others. Moreover, we have relied as
to matters of fact, to the extent we have deemed proper, upon certificates and
representations of the Company's officers and management.

     This letter is limited to the matters set forth herein, and no matter may
be inferred or implied beyond the matters expressly stated in this letter.  No
inference as to our independent review of any information set forth in the
Registration Statement should be drawn from the fact of our representation of
the Company.  We assume no obligation to advise you, subsequent to the delivery
of this letter, of any matters that could result in a change in the opinions or
beliefs set forth herein.  This letter has been prepared solely for your use in
connection with the Purchase of the Shares under the Registration Statement, and
may not be used for any other purpose, or be relied upon by any other person or
entity.  It should not be quoted in whole or in part or otherwise be referred
to, nor be filed with nor furnished to any governmental agency or other person
or entity, without the prior written consent of this firm.

     The statements made herein are limited in all respects to United States
patents and patent applications. The statements made herein are also limited in
all regards by the statements made in the Registration Statement. The statements
made herein are also limited to matters on which we can advise the Company
without breach of any duty owed to other clients of our firm, and should not be
construed as expressing any opinion, view or waiver with respect to any other
clients' patents, patent applications or other rights.

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