UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, DC 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934
(Amendment No.)*


Onconova Theraupetics Inc.
(Name of Issuer)


Common Stock
(Title of Class of Securities)


68232V108
(CUSIP Number)


April 21, 2017
(Date of Event Which Requires Filing of this Statement)


       Check the appropriate box to designate the rule pursuant to which
this Schedule is filed:

[_]  Rule 13d-1(b)

[X]  Rule 13d-1(c)

[_]  Rule 13d-1(d)

__________
       *The remainder of this cover page shall be filled out for a reporting
person's initial filing on this form with respect to the subject class of 
securities, and for any subsequent amendment containing information which 
would alter the disclosures provided in a prior cover page.
       The information required in the remainder of this cover page shall 
not be deemed to be filed for the purpose of Section 18 of the Securities 
Exchange Act of 1934 (Act) or otherwise subject to the liabilities of that 
section of the Act but shall be subject to all other provisions of the Act 
(however, see the Notes).
?
CUSIP No.
68232V108





1. 
NAME OF REPORTING PERSONS








Sabby Healthcare Master Fund, Ltd.




2.
CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)


(a)  [_]


(b)  [X]



3.
SEC USE ONLY










4.
CITIZENSHIP OR PLACE OF ORGANIZATION





Cayman Islands




NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH



5.
SOLE VOTING POWER





0




6.
SHARED VOTING POWER





 702,896




7.
SOLE DISPOSITIVE POWER





0




8.
SHARED DISPOSITIVE POWER





 702,896




9.
AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON




 702,896




10. 
CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN 
SHARES (SEE INSTRUCTIONS)



[_]






11.
PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)





7.61




12.
TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

              CO?
CUSIP No.
68232V108





1. 
NAME OF REPORTING PERSONS








Sabby Volatility Warrant Master Fund, Ltd.




2.
CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)


(a)  [_]


(b)  [X]



3.
SEC USE ONLY










4.
CITIZENSHIP OR PLACE OF ORGANIZATION





Cayman Islands




NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH



5.
SOLE VOTING POWER





0




6.
SHARED VOTING POWER





 86,500




7.
SOLE DISPOSITIVE POWER





0




8.
SHARED DISPOSITIVE POWER





 86,500




9.
AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON




 86,500




10. 
CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN 
SHARES (SEE INSTRUCTIONS)



[_]






11.
PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)





0.94




12.
TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

              CO?

CUSIP No.
68232V108





1. 
NAME OF REPORTING PERSONS








Sabby Management, LLC




2.
CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)


(a)  [_]


(b)  [X]



3.
SEC USE ONLY










4.
CITIZENSHIP OR PLACE OF ORGANIZATION





Delaware, USA




NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH



5.
SOLE VOTING POWER





0




6.
SHARED VOTING POWER





 789,396




7.
SOLE DISPOSITIVE POWER





0




8.
SHARED DISPOSITIVE POWER





 789,396




9.
AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON




 789,396




10. 
CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN 
SHARES (SEE INSTRUCTIONS)



[_]






11.
PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)





8.55




12.
TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

              OO
CUSIP No.
68232V108





1. 
NAME OF REPORTING PERSONS








Hal Mintz




2.
CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)


(a)  [_]


(b)  [X]



3.
SEC USE ONLY










4.
CITIZENSHIP OR PLACE OF ORGANIZATION





USA




NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH



5.
SOLE VOTING POWER





0




6.
SHARED VOTING POWER





 789,396




7.
SOLE DISPOSITIVE POWER





0




8.
SHARED DISPOSITIVE POWER





 789,396




9.
AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON




 789,396




10. 
CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN 
SHARES (SEE INSTRUCTIONS)



[_]






11.
PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)





8.55




12.
TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

              IN?

CUSIP No.
68232V108



Item 1.
(a).
Name of Issuer:







Onconova Theraupetics Inc.



(b).
Address of issuer's principal executive offices:







375 Pheasant Run
Newtown, PA 18940

Item 2.
(a).
Name of person filing:







Sabby Healthcare Master Fund, Ltd.
Sabby Volatility Warrant Master Fund, Ltd.
Sabby Management, LLC 
Hal Mintz




(b).
Address or principal business office or, if none, residence:




Sabby Healthcare Master Fund, Ltd.
c/o Ogier Fiduciary Services (Cayman) Limited
89 Nexus Way, Camana Bay
Grand Cayman KY1-9007
Cayman Islands

Sabby Volatility Warrant Master Fund, Ltd.
c/o Ogier Fiduciary Services (Cayman) Limited
89 Nexus Way, Camana Bay
Grand Cayman KY1-9007
Cayman Islands

Sabby Management, LLC
10 Mountainview Road, Suite 205
Upper Saddle River, New Jersey 07458

Hal Mintz
c/o Sabby Management, LLC
10 Mountainview Road, Suite 205
Upper Saddle River, New Jersey 07458







(c).
Citizenship:




Sabby Healthcare Master Fund, Ltd. - Cayman Islands
Sabby Volatility Warrant Master Fund, Ltd. - Cayman Islands
Sabby Management, LLC - Delaware, USA
Hal Mintz - USA







(d).
Title of class of securities:







Common stock (the Common Stock), par value $0.001



(e).
CUSIP No.:







68232V108


Item 3.
If This Statement is filed pursuant to Section 240.13d-1(b) or 240.13d-2(b),
or (c), check whether the person filing is a


(a)
[_]
Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o).


(b)
[_]
Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c).


(c)
[_]
Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c).


(d)
[_]
Investment company registered under section 8 of the Investment Company Act 
of 1940 (15 U.S.C. 80a-8).


(e)
[_]
An investment adviser in accordance with Section 240.13d-1(b)(1)(ii)(E);


(f)
[_]
An employee benefit plan or endowment fund in accordance with Section 
240.13d-1(b)(1)(ii)(F);


(g)
[_]
A parent holding company or control person in accordance with Section 
240.13d-1(b)(1)(ii)(G);



(h)
[_]
A savings association as defined in Section 3(b) of the Federal Deposit 
Insurance Act (12 U.S.C.1813);


(i)
[_]
A church plan that is excluded from the definition of an investment company
under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 
80a-3);


(j)
[_]
A non-U.S. institution in accordance with Section 240.13d-1(b)(1)(ii)(J); 


(k)
[_]
Group, in accordance with Section 240.13d-1(b)(1)(ii)(K).  If filing as a 
non-U.S. institution in accordance with Section 240.13d-1(b)(1)(ii)(J), 
please specify the type of institution: 







Item 4.
Ownership.


Provide the following information regarding the aggregate number and 
percentage of the class of securities of the issuer identified in Item 1.


(a)
Amount beneficially owned:

Sabby Healthcare Master Fund, Ltd. -  702,896

Sabby Volatility Warrant Master Fund, Ltd. -  86,500

Sabby Management, LLC -  789,396

Hal Mintz -  789,396


(b)
Percent of class:

Sabby Healthcare Master Fund, Ltd. - 7.61%

Sabby Volatility Warrant Master Fund, Ltd. - 0.94%

Sabby Management, LLC - 8.55%

Hal Mintz - 8.55% 





 
(c)
Number of shares as to which the person has:

 
 
Sabby Healthcare Master Fund, Ltd.

 
 
(i)
Sole power to vote or to direct the vote
0
,
 
 
 
 
 
 
 
(ii)
Shared power to vote or to direct the vote
 702,896
,
 
 
 
 
 
 
 
(iii)
Sole power to dispose or to direct the disposition of
0
,
 
 
 
 
 
 
 
(iv)
Shared power to dispose or to direct the disposition of
 702,896
.
 
 
 

 
 
 
 
Sabby Volatility Warrant Master Fund, Ltd.

 
 
(i)
Sole power to vote or to direct the vote
0
,
 
 
 
 
 
 
 
(ii)
Shared power to vote or to direct the vote
 86,500
,
 
 
 
 
 
 
 
(iii)
Sole power to dispose or to direct the disposition of
0
,
 
 
 
 
 
 
 
(iv)
Shared power to dispose or to direct the disposition of
 86,500
.


 
 
Sabby Management, LLC 

 
 
  (i)
Sole power to vote or to direct the vote
0
,
 
 
 
 
 
 
 
 (ii)
Shared power to vote or to direct the vote
 789,396
,
 
 
 
 
 
 
 
 (iii)
Sole power to dispose or to direct the disposition of
0
,
 
 
 
 
 
 
 
 (iv)
Shared power to dispose or to direct the disposition of
 789,396
.
 
 
 
 
 

 
 
Hal Mintz 

 
 
 (i)
Sole power to vote or to direct the vote
0
,
 
 
 
 
 
 
 
 (ii)
Shared power to vote or to direct the vote
 789,396
,
 
 
 
 
 
 
 
 (iii)
Sole power to dispose or to direct the disposition of
0
,
 
 
 
 
 
 
 
 (iv)
Shared power to dispose or to direct the disposition of
 789,396
.
 
 
 
 
 



As calculated in accordance with Rule 13d-3 of the Securities Exchange Act 
of 1934, as amended, (i) Sabby Healthcare Master Fund, Ltd. and 
Sabby Volatility Master Fund, Ltd. beneficially own 702,896 and 86,500 
shares of the Issuer's common stock (Common Stock), respectively, 
representing approximately 7.61% and 0.94% of the Common Stock, 
respectively, and (ii) Sabby Management, LLC and Hal Mintz each beneficially 
own 789,396 shares of the Common Stock, representing approximately 8.55% 
of the Common Stock. Sabby Management, LLC and Hal Mintz do not directly own 
any shares of Common Stock, but each indirectly owns 789,396 shares of 
Common Stock. Sabby Management, LLC, a Delaware limited liability company, 
indirectly owns  789,396 shares of Common Stock because it serves as the 
investment manager of Sabby Healthcare Master Fund, Ltd. and 
Sabby Volatility Warrant Master Fund, Ltd., Cayman Islands companies.
Mr. Mintz indirectly owns 789,396 shares of Common Stock in his capacity 
as manager of Sabby Management, LLC.


Item 5.
Ownership of Five Percent or Less of a Class.


If this statement is being filed to report the fact that as of the date 
hereof the reporting person has ceased to be the beneficial owner of more 
than five percent of the class of securities, check the following  [ ].






?
Item 6.
Ownership of More Than Five Percent on Behalf of Another Person.





Not applicable



Item 7.
Identification and Classification of the Subsidiary Which Acquired the 
Security Being Reported on by the Parent Holding Company or Control Person.





Not applicable



Item 8. 
Identification and Classification of Members of the Group.





Not applicable



Item 9.
Notice of Dissolution of Group.





Not applicable



?
Item 10.
Certification.




By signing below I certify that, to the best of my knowledge and belief, the
securities referred to above were not acquired and are not held for the 
purpose of or with the effect of changing or influencing the control of the 
issuer of the securities and were not acquired and are not held in 
connection with or as a participant in any transaction having that purpose 
or effect.



?
SIGNATURE

       After reasonable inquiry and to the best of my knowledge and belief,
I certify that the information set forth in this statement is true, complete 
and correct.

May 1, 2017

(Date)





Sabby Healthcare Master Fund, Ltd.

By: /s/ Harry Thompson	
	Name:  Harry Thompson
 Title:   Authorized Person of TDF Management Ltd.,    
a Director


Sabby Volatility Warrant Master Fund, Ltd.

By: /s/ Harry Thompson	
	Name:  Harry Thompson
 Title:   Authorized Person of TDF Management Ltd.,    
a Director


Sabby Management, LLC*

By: /s/ Robert Grundstein	
	Name:  Robert Grundstein
       Title:   Chief Operating Officer







/s/ Hal Mintz*					
 Hal Mintz

*This Reporting Person disclaims beneficial ownership over the securities 
reported herein except to the extent of its pecuniary interest therein. 

The original statement shall be signed by each person on whose behalf the 
statement is filed or his authorized representative.  If the statement is 
signed on behalf of a person by his authorized representative other than an 
executive officer or general partner of the filing person, evidence of the 
representative's authority to sign on behalf of such person shall be filed 
with the statement, provided, however, that a power of attorney for this 
purpose which is already on file with the Commission may be incorporated by 
reference.  The name and any title of each person who signs the statement 
shall be typed or printed beneath his signature.

Note.  Schedules filed in paper format shall include a signed original and 
five copies of the schedule, including all exhibits. See s.240.13d-7 for 
other parties for whom copies are to be sent. 

Attention.  Intentional misstatements or omissions of fact constitute 
Federal criminal violations (see 18 U.S.C. 1001).

EXHIBIT 1
----------

JOINT FILING AGREEMENT

       The undersigned hereby agree that this Statement on Schedule 13G with 
respect to the beneficial ownership of shares of Common Stock of Rexahn 
Pharmaceuticals, Inc. is filed jointly, on behalf of each of them.


Dated:  May 1, 2017


Sabby Healthcare Master Fund, Ltd.

By: /s/ Harry Thompson	
     Name:  Harry Thompson
     Title:   Authorized Person of TDF Management 
Ltd.,    a Director 

Sabby Volatility Warrant Master Fund, Ltd.

By: /s/ Harry Thompson	
     Name:  Harry Thompson
     Title:   Authorized Person of TDF Management 
Ltd.,    a Director



Sabby Management, LLC

By: /s/ Robert Grundstein	
	Name:  Robert Grundstein
       Title:   Chief Operating Officer




/s/ Hal Mintz					
 Hal Mintz