Exhibit 10.27.1

CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY BRACKETS, HAS BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO
RULE 24b-2 OF THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.

AMENDED AND RESTATED SECOND AMENDMENT TO LEASE

THIS AMENDED AND RESTATED SECOND AMENDMENT TO LEASE ("Amendment") is made and entered into as of the
9th day of December, 2002, by and between CATELLUS DEVELOPMENT CORPORATION, a Delaware corporation ("Landlord"), and ALLOS
THERAPEUTICS, INC., a Delaware corporation ("Tenant").

R E C I T A L S:

A.    Landlord
and Tenant entered into that certain Office Lease dated as of April 4, 2001 (the "Original Lease"), as
amended by that certain First Amendment to Lease and Commencement Date Memorandum dated as of November 1, 2002 ("First Amendment"), and that
certain Second Amendment to Lease dated November 12, 2002 ("Second Amendment"), whereby Tenant leased certain office space in the building
located at 11080 CirclePoint Road in Westminster, Colorado. The Original Lease, as amended by the First Amendment and Second Amendment, is referred to herein as the
"Lease."

B.    By
this Amendment, Landlord and Tenant desire amend and restate the Second Amendment in its entirety.

C.    Unless
otherwise defined herein, capitalized terms as used herein shall have the same meanings as given thereto in the Lease.

NOW,
THEREFORE, in consideration of the foregoing recitals and the mutual covenants contained herein, and for other good and valuable consideration, the receipt and sufficiency of which
are hereby acknowledged, the parties hereto agree as follows:

A G R E E M E N T:

1.The Existing Premises.Landlord currently leases to Tenant that certain office space containing 31,248
rentable square feet located on the second (2nd) floor of the Building and known as Suite 200 (the "Existing Premises").

2.Expansion of the Premises.That certain space located on the ground floor of the Building consisting of
approximately 12,129 rentable square feet, as outlined on the floor plan attached hereto as Exhibit A and made a part hereof, is referred to herein as the "Expansion
Space." Tenant shall lease the Expansion Space effective as of January 1, 2003 (the "Expansion Commencement Date").
Accordingly, effective upon the Expansion Commencement Date, the Existing Premises shall be increased to include the Expansion Space. Such addition of the Expansion Space to the Existing Premises
shall, effective as of the Expansion Commencement Date, increase the number of rentable square feet leased by Tenant in the Building to a total of 43,377 rentable square feet, subject to verification
pursuant to Section 3 below. Effective as of the Expansion Commencement Date, all references in the Lease to the "Premises" shall mean and refer to the Existing Premises as expanded by the
Expansion Space. The period from the Expansion Commencement Date through the Expiration Date is referred to herein as the "Expansion Term."

3.Verification of Rentable Square Footage.The rentable square footage of the Expansion Space shall be subject
to verification in accordance with the provisions of Section 2.1 of the Original Lease, except that Landlord shall cause its space measurement consultant to provide such verification within
thirty (30) days following the Expansion Commencement Date. If such verification results in a rentable square footage of the Expansion Space that is different than that set forth in
Section 2 above, then the parties shall further amend the Lease to modify all amounts, percentages and figures appearing or

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referred to in this Amendment to conform to such corrected rentable square footage (including, without limitation, the Base Rent, and Tenant's Percentage Share and the TI Allowance).

4.Base Rent.During the Expansion Term, and in addition to the Base Rent for the Existing Premises, Tenant
shall pay Base Rent for the Expansion Space as follows (although Base Rent for the Existing Premises and the Expansion Space are separately identified, such amounts shall be a single and
non-severable rental obligation):

|Period of
Expansion Term   |  | Annual Base Rent Per Rentable
Square Foot |  | Annual Base Rent |  | Monthly Base Rent
|-------------------------- |  | ----------------------------------------- |  | ---------------- |  | -----------------
|1-12
(1/01/03 - 12/31/03)  |  | [*]                                       |  | [*]              |  | [*]              
|13-15
(1/01/04 - 3/31/04)  |  | [*]                                       |  | [*]              |  | [*]              
|16-45
(4/01/04 - 9/30/06)  |  | [*]                                       |  | [*]              |  | [*]              
|46-70
(10/1/06 - 10/31/08) |  | [*]                                       |  | [*]              |  | [*]              

5.Tenant's Percentage Share.Commencing on July 1, 2003, and continuing thereafter during the Expansion
Term, Tenant's Percentage Share shall be increased to 28.72%. The parties acknowledge that Tenant shall have no obligation to pay Real Property Taxes and Operating Expenses attributable to the
Expansion Space during the period from the Expansion Commencement Date through June 30, 2003.

6.Exclusion of Variable Operating Expenses.Operating Expenses attributable to the Expansion Space shall
exclude those Operating Expenses that vary with occupancy, such as janitorial expenses and utility costs (other than those attributable to the Common Facilities), until the Tenant Improvements (as
defined in Exhibit B) are substantially completed in all or any portion of the Expansion Space.

7.Letter of Credit.The schedule of Adjustment Dates for reducing the Stated Amount of the Letter of Credit as
set forth in Section 4.4.1 of the Original Lease is deleted and the following is substituted therefor:

Anniversary of Commencement Date

Total Stated Amount5th (10/01/06)

[*]6th (10/01/07)

[*]7th (10/01/08)

[*]


Notwithstanding
anything to the contrary contained in Section 4.4.1 of the Original Lease, if Tenant gives Landlord written notice that Tenant's net income for any consecutive
twelve (12)-month period exceeds [*], together with evidence reasonably acceptable to Landlord verifying that such net income threshold has been met (and a certification from
Tenant's Chief Financial Officer that all such evidence is true and correct), then Landlord shall return the Letter of Credit to Tenant; provided, however, in no event shall Landlord be obligated to
return the Letter of Credit to Tenant at any time an Event of Default exists or any circumstance exists that would, with notice or lapse of time, or both, constitute an Event of Default.

8.Cash Security Deposit.The date by which Tenant shall deposit with Landlord the cash Security Deposit
pursuant to Section 4.4.2 of the Original Lease is extended from the sixth (6th) anniversary of the Rent Commencement Date to the seventh (7th) anniversary of the
Commencement Date (10/1/08); provided, however, if the Letter of Credit is released prior to the seventh (7th) anniversary of the Commencement Date pursuant to the provisions of
Section 7 above, then Tenant shall, concurrently

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with Landlord's delivery of the Letter of Credit to Tenant, deliver the cash Security Deposit to Landlord.

9.Tenant Improvements.The Tenant Improvements (as defined in Exhibit B) in the Expansion Space shall be
installed and constructed in accordance with the terms of the Tenant Work Letter attached hereto as Exhibit B and made a part hereof. The parties acknowledge that there is no required time
schedule to construct the Tenant Improvements, and Tenant shall, subject to Landlord's reasonable approval, be entitled to designate with the Tenant Improvements are to be constructed. Tenant
acknowledges that construction of the Tenant Improvements may occur during the Expansion Term and that the performance of such work shall not be deemed a constructive eviction nor shall Tenant be
entitled to any abatement of Rent in connection therewith. In addition, Landlord shall not be liable for any damage to property, injury to persons or damage to Tenant's business caused by the
construction of the Tenant Improvements during the Expansion Term.

10.Parking.During the Expansion Term, Tenant shall rent from Landlord an additional forty-nine
(49) parking spaces for use in the Building's parking facility. Tenant's rental and use of such additional parking spaces shall be in accordance with, and subject to, all provisions of
Section 2.4 of the Original Lease.

11.Subletting.The limitation on the number of subparcels under clause (viii) of Section 18.1 of
the Original Lease shall only apply to the Existing Premises, and the number of subparcels within the Expansion Space shall be subject to Landlord's reasonable approval.

12.Brokers.Each party represents and warrants to the other that no broker, agent or finder negotiated or was
instrumental in negotiating or consummating this Amendment other than Equis Corporation and CB Richard Ellis ("Brokers"). Landlord shall pay a brokerage
commission to Brokers in accordance with separate agreements between and Landlord and Brokers. Subject to the foregoing, each party agrees to defend, indemnify and hold harmless the other party from
and against any claim for a commission or finder's fee by any person or entity who claims or alleges that they were retained or engaged by the indemnifying party or at the request of such party in
connection with this Amendment.

13.Tenant Representations.Each person executing this Amendment on behalf of Tenant represents and warrants to
Landlord that, and Tenant shall, at Landlord's request, provide Landlord with evidence that: (a) Tenant has full right and authority to enter into this Amendment and to perform all of Tenant's
obligations hereunder; and (b) each person signing this Amendment on behalf of Tenant is duly and validly authorized to do so.

14.Second Amendment.This Amendment amends and restates the Second Amendment in its entirety, such that the
provisions in the Second Amendment shall have no effect.

15.No Further Modification.Except as set forth in this Amendment, all of the terms and provisions of the Lease
shall apply with respect to the Expansion Space and shall remain unmodified and in full
force and effect. Effective as of the date hereof, all references to the "Lease" shall refer to the Lease as amended by this Amendment.

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IN
WITNESS WHEREOF, this Amendment has been executed as of the day and year first above written.

| |  | "Landlord":                                             
| |  | --------------------------------------------------------
| |  | CATELLUS DEVELOPMENT CORPORATION,
a Delaware corporation
| |  | By:                                                     
| |  | By:                                                     
| |  |                                                         
| |  |                                                         
| |  | "Tenant":                                               
| |  | ALLOS THERAPEUTICS, INC.,
a Delaware corporation        
| |  | By:                                                     
| |  |                                                         
| |  |                                                         
| |  | By:                                                     
| |  |                                                         
| |  |                                                         

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EXHIBIT A        OUTLINE OF EXPANSION SPACE

[graphic]

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EXHIBIT B        TENANT WORK LETTER

This Work Letter ("Work Letter") is attached to the Amendment as Exhibit B and incorporated into the
Amendment by reference. Capitalized terms used herein and not defined herein shall have the respective meanings set forth in the Lease.

1.Landlord's Work.Landlord has constructed the Building in accordance with the plans and specifications
described in Schedule I attached hereto.

2.Tenant Improvements.



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2

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3

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3.Completion of the Tenant Improvements.



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5

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SCHEDULE I TO EXHIBIT B        BUILDING PLANS AND SPECIFICATIONS        WESTMINSTER        BASE BUILDING CORE AND SHELL

|Parking Stalls:         |  | Parking is provided at 4.1 spaces per 1,000 square feet of rentable building area.                                                                                                                                                                                                                                                                                                                                                  
|----------------------- |  | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|Parking Lot Lighting:   |  | Parking lot lighting is provided, designed to supply an average to minimum ratio of approximately 1.0 foot candles/SF.                                                                                                                                                                                                                                                                                                              
|Sitework:               |  | Asphalt concrete paving in all traffic and parking areas, concrete curb and gutter per approved development plans.                                                                                                                                                                                                                                                                                                                  
|Landscaping:            |  | Landscape planting materials and irrigation of all planting areas per approved development plans.                                                                                                                                                                                                                                                                                                                                   
|Building Structure:     |  | Precast concrete frame with precast concrete floor and roof structure and approximately 4-inch concrete topping slab.                                                                                                                                                                                                                                                                                                               
|Floor Loading Criteria: |  | Live load is approximately 50 psf in general office area, with approximately 100 psf at corridor and interior office area immediately adjacent to corridor. Partition load is approximately 20 psf.                                                                                                                                                                                                                                 
|Ceiling Heights:        |  | Clear ceiling heights are approximately 12'-2" feet at ground floor tenant areas, and approximately 9'-2" at floors 2, 3, 4 and 5 tenant areas. Typical structure to structure clearance is approximately 14.5 feet at ground floor 14'-8" from floor to
bottom of "T" at ground floor, and 11'-8" approximately 11. 5 feet from floor to bottom of "T" at floors 2, 3, 4 and 5. Clearances may be 12 inches less at beam locations.
|Building Skin:          |  | Precast architectural concrete spandrel panels with continuous glazing in between. Full height glazing at most locations. See elevation drawings for detail.                                                                                                                                                                                                                                                                        
|Roofing:                |  | 60 mil EPDM roof membrane, ballasted, over 2.6" rigid polyisocyanruate board. R-value of 19.                                                                                                                                                                                                                                                                                                                                        
|Perimeter Walls:        |  | Perimeter, exterior walls to be insulated only, no drywall.                                                                                                                                                                                                                                                                                                                                                                         
|Core Service Areas:     |  | 1. Sound attenuation is provided to meet NC35 levels.
2. Janitor's closet provided on each floor.
3. Finished doors provided for all service rooms.
4. Door frames to be anodized aluminum for all core doors.
5. One drinking fountain location each floor, with two fountains, one meeting ADA requirements.                                                                                                                      
|Rest Rooms:             |  | Rest rooms to have ceramic tile on floors, and full height on wet walls. Toilet partitions to be ceiling hung stainless steel. Vanity tops to be granite. Rest rooms to be ADA compliant.                                                                                                                                                                                                                                           
|Shower Facilities:      |  | Ground floor restrooms to include two shower stalls each in men's and women's. One shower stall in each to be ADA compliant.                                                                                                                                                                                                                                                                                                        
|                        |  |                                                                                                                                                                                                                                                                                                                                                                                                                                     

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|Telephone Room:     |  | Main telephone/fiber optic room provided at ground floor, approximately 20 feet by 10 feet. Conduit to be stubbed into room for telephone and 3 possible fiber optic providers. Approximately 6 foot by 9 foot communications rooms provided on floors 2,
3, 4 and 5.                                                                                                                                                                                             
|------------------- |  | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|Elevators:          |  | Hydraulic elevators, 3,500 lb. capacity provided. Interior cab height to be approximately 10 feet, with suspended ceiling at approximately 9 feet. Finishes will be compatible with main lobby. Freight elevator to be supplied with protective blankets.
Waiting time will be average of 27-29 seconds, with 5 minute handling capacity of 13% of building population (upper floors only). Elevators to be ADA compliant, and provided with emergency telephones.
|Fire Protection:    |  | Complete fire sprinkler system in accordance with applicable codes for office occupancy. Fireproofing of the Building's structural steel as specified on the structural plans for the Building as approved by the City of Westminster (a copy of which
plans Tenant acknowledges receiving).                                                                                                                                                                      
|Plumbing Systems:   |  | Complete plumbing system for domestic water service, sanitary sewer service, and roof drainage. Water and sanitary systems will be accessible to tenant areas for future connections for convenience sinks and other uses.                                                                                                                                                                                                                                        
|HVAC:               |  | HVAC system is provided with rooftop units, total capacity approximately 460 tons, of approximately 350 sf per ton. Primary trunk ducts and exterior zone VAV boxes provided at approximately 1 per 1,100 SF. Exterior zone VAV boxes are provided with
electric reheat. No distribution ducting or diffusers are included at these exterior zone boxes.                                                                                                          
|                    |  | Energy management system provided, with remote computer monitoring capability. Tenant metering capability also included in system.                                                                                                                                                                                                                                                                                                                                
|                    |  | HVAC Design criteria for cooling load allowed include the following:                                                                                                                                                                                                                                                                                                                                                                                              
|                    |  | 2 watts per SF for lighting;
1.5 watts per SF for office equipment;
150 SF per person.                                                                                                                                                                                                                                                                                                                                                                            
|Electrical Service: |  | The building is provided with primary electrical service, 277/480 volts, 3 phase, with main disconnects in the main electrical room on the first floor. Electrical distribution panel rooms are provided two per floor adjacent to stairwells.                                                                                                                                                                                                                    
|                    |  | Electrical service will provide total capacity of 27 watts per square foot, generally allocated as follows:                                                                                                                                                                                                                                                                                                                                                       
|                    |  | 15 watts per SF for HVAC loads;
3 watts per SF for lighting;
6.5 watts per SF for tenant equipment loads;
2.5 watts per SF spare power;
A pad area for a future generator to be included in the building shell.                                                                                                                                                                                                                                                   
|Fire Alarm:         |  | Fire alarm panel is provided, including fire alarm devices as required by code in core and common areas.                                                                                                                                                                                                                                                                                                                                                          
|                    |  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                   

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|Security |  | A card access system to be provided at the main entry doors of the building. Elevator card access also to be available based on tenant needs (but at Tenant's sole cost and expense).
|-------- |  | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

[*]
= CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY BRACKETS, HAS BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION
PURSUANT TO RULE 24b-2 OF THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.

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