Exhibit 4.6


                               LICENSING AGREEMENT

         This  Agreement  is made  this  3rd day of May,  1995  between  Yorkton
Medical Inc., a corporation  incorporated  under the laws of Ontario and located
at The Exchange Tower, 2 First Canadian  Place,  Suite 3640,  Toronto,  Ontario,
Canada M5X 1J8 ("YM") , and whose facsimile number in Canada is 416-864-1043,  ,
and CIMAB S.A., a corporation  incorporated  under the laws of Cuba,  located at
Calle 206, Suite 1926, ent. 19 y 21, Atabey,  Havana, Cuba ("CIMAB"),  and whose
facsimile number in Cuba is 7-333509.

BACKGROUND

1.  Centro de  Inmulogia  Molecular  ("CIM") has  appointed  CIMAB to act as its
'iancoU\~r.C1nac'.a agent to negotiate and sign this Agreement.

2. CIM owns and has given CIMAB the right to license cer1ain  technology  Paris.
France relating to the Products identified in this Agreement.

CIMAB  and YM  wish  to  establish  a long  term  relationship  to  exploit  the
technology and to commercialize the Products identified in this Agreement and to
exploit other technology and to commercialize  other products of CIM that may be
added through future agreements.

         Therefore,  in  consideration  of the mutual  covenants and  agreements
contained in this Agreement, YM and CIMAB agree as follows:

1. DEFINITIONS

AFFILIATED COMPANY -means any company that is controlled  directly or indirectly
by one of the par1ies,  or any company that directly or indirectly  controls one
of the par1ies,  or any company that is directly or  indirectly  controlled by a
company which also directly or indirectly  controls one of the par1ies,  so that
Affiliated Company shall include any parent or subsidiary of one of the par1ies,
or any direct or indirectly held subsidiary of one of the parties.

BEST AVAILABLE PRICE -means 90% of the best available price for the Manufacture,
supply  and  delivery  of the  Product to Toronto  (FOB  Toronto),  or any other
location  designated by CIMYM in writing,  until such time as there are positive
Net  Revenues  at which time best  available  price  shall mean 100% of the best
available  price for the  Manufacture,  supply and  delivery  of the  Product to
Toronto (FOB Toronto), or any other location designated by CIMYM in writing.

CGMP -means  Current Good  Manufacturing  Practices as established by the United
States Food and Drug  Administration  and the Canadian Health  Protection Branch
from time to time.

CIMYM -means a company to be incorporated by YM and referred to in Article 12 of
this  Agreement.  YM shall,  immediately  upon  evidence  satisfactory  to it of
approval of this  Agreement from the  Government of Cuba,  incorporate  CIMYM to
which shall be immediately  trarl5fcrred  the rights and obligations  under this
Agreement.

CUBA -means the Republic of Cuba.

EFFECTIVE  DATE -means the date that is the earlier of (i) six (6) months  after
the date of receipt of evidence  satisfactory to YM of necessary  approvals from
the Government of Cuba for this  Agreement,  and (ii) the date that YM commences
pre-clinical trials or Marketing of the Product.

FINISH  -means to convert bulk Product into final dosage form and to package and
label the Product and Finishing has a corresponding meaning.

IMPROVEMENTS -means a product or process the use or sale of which would infringe
a valid claim of one or more of the Patents.


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MANUFACTURE  -means  to  manufacture  the  Product,   and  Manufacturing  has  a
corresponding meaning.

MARKET -means to test, register, market and sell the Product and Marketing has a
corresponding meaning.

NET REVENUES  -means the total of all money  received by CIMYM from sales of the
Product and from rights to Finish or Market the  Product in the  Territory  less
operating  expenses  associated  with  the  commercialization  of  the  Product,
including the following:  (i) pre-clinical and clinical trial costs, (ii) sales,
general and  administrative  costs, (iii) costs of goods sold, where applicable,
(iv) research and development  costs,  (v) interest  expenses,  if any. and (vi)
capital expenditures. Money received means money received less trade-allowances,
credit or refunds for returned or defective Product, and allowances for doubtful
debts.

PATENTS -means all patents,  patent applications and other intellectual property
rights relating to the Products and includes the patents and patent applications
identified in Schedule 1 .

PERSON  -or  any  word  or  expression  descriptive  of  a  person,  includes  a
corporation,  partnership,  sole  proprietorship,  association,  organization or
centre.

PRODUCTS  -means  products for passive  immunotherapy  of cancer directed toward
Epidermal  Growth Factor (EGF) or Epidermal  Growth  Factor-Receptor  (EGF-R) as
targets,  and includes (i) monoclonal  antibodies  against EGF, (ii)  monoclonal
antibodies  against  EGF-R,  (iii) murine  monoclonal  antibodies  (or any other
monoclonal  antibodies including those of human and non- human primates) against
EGF, (iv) recombinant monoclonal antibodies (including chimeric,  humanized,  or
derived from human or any other species)  against EGF-R, (v) combinations of any
of  these   monoclonal   antibodies  with   gangliosides,   (vi)  any  segments.
derivatives,  or  analogues of these  antibodies,  and includes any product made
using such antibodies. their segments. derivatives or their analogues, (vii) any
monoclonal  antibodies  which  recognize  EGF or EGF-R,  and (viii) the products
claimed in the Patents for treatment of cancer,  and includes the products,  the
specifications of which are set out in Schedule 3.

STANDARDS  -means  cGMP and other  standards  prescribed  by  health  regulatory
authorities  in the  Territory  from  time  to  time  during  the  term  of this
Agreement.

TECHNOLOGY  -means  confidential  information  relating to (i) the  Finishing or
Marketing of the Product.  or relating to technology  pertaining to the Products
(ii) the Patents including  information in the Patents relating to the Products,
relating to Finishing or Marketing the Products. or relating to chemistry of the
Products, and (iii) Improvements. .

TERRITORY -means Europe, Canada, the United States of America, Japan, Australia.
Taiwan.  Singapore,  Thailand, Hong Kong, South Korea, Malaysia,  Indonesia, the
Philippines, and any other country that may be added to this Agreement by mutual
agreement from time to time.

TRADE-MARK -means a trade-mark of CIMAB used in association with the Product. ..
YM means YM and its affiliated companies and its sub-licensees.

2. POWER OF ATTORNEY

N/A

3. LICENSE

(1) CIMAB grants to YM the exclusive  right to Finish and Market the Products jn
the Territory using the Technology. This exclusive license includes the right to
sub-license  the rights granted under this  Agreement to any other Person.  This
license includes the right to use the Trade-mark or any other trade-marks in the
Territory in association with the Products.

(2) YM shall commence  Marketing by the Effective  Date. If YM fails to commence
Marketing  by that time.  CIMAB  shall have the right to convert  the  exclusive
license granted under this Agreement to a non-exclusive  license to YM to Finish
and Market the Product in the Territory using the Technology by providing notice
in writing to YM.


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4. REPRESENTATIONS' AND WARRANTIES

CIMAB represents and warrants that:

o   nothing in this Agreement is contrary to or unenforceable under the laws of

o   Cuba.

o   CIMAB has the right,  power and  authority to represent and act as agent for
    CIM and that this authority will survive the termination of this license.

o   CIMAB has the authority to grant the license granted to YM.

o   To the best of CIMAB's knowledge CIM owns tile Technology  absolutely,  free
    and clear of any liens or claims.

o   CIMAB has not granted any currently valid licenses to any Persons other than
    YM to use the Technology in any country within the Territory.

o   CIMAB is not aware of any actual or  potential  claim by any Person that CIM
    does not own the Technology or cannot use the Technology.

o   CIMAB is not aware of any  challenge to CIM's  ownership of, or the validity
    of, the Patents.

o   CIMAB is not aware of any rights that could be infringed in the Territory by
    the use of the Technology or by the  Manufacture,  Finishing or Marketing of
    the Products in the Territory.

YM represents and warrants that:

o   nothing in this agreement is contrary to or unenforceable  under the laws of
    Canada

o   YM is duly incorporated  under the laws of the Province of Ontario,  Canada,
    is a corporation in good standing and may undertake this Agreement.

5. DISCLOSURE OF TECHNOLOGY BY CIMAB

Immediately  upon the  execution of this  Agreement and at the end of each month
during the term,  CIMAB shall  disclose to YM all  Technology to assist CIMYM in
fulfilling its obligations under this Agreement, including (i) all manufacturing
procedures and processes, raw material lists and specifications, equipment lists
and  specifications,  and all quality  assurance  and other in vitro and in vivo
test  methodologies,  validations  and results:  (ii)  reports of all  stability
studies;  (iii)  reports of all animal and human  studies:  (iv)  reports of all
clinical  efficacy and safety  studies:  (v) reports of all other  pre-clinical,
pharmacological and toxicological studies: (vi) all reports or other information
relating  to any  potential  threat  or risk to  users of the  Products,  or any
contra-indications  to the use of the Technology or the Products:  and (vii) all
knowledge and  experience in the Finishing and Marketing of the Products.  CIMAB
shall  grant  CIMYM  access to all plant  master  files  that are  submitted  to
regulatory authorities in the Territory from time to time for the plant in which
the Products are made.

6. VISITS

(1)  Technical  personnel  of CIMYM  and YM shall  have the  right to visit  the
facilities  of CIM to review the  Technology.  Technical  personnel of CIM shall
have the right to visit the  facilities of CI~.~YM to review the  application of
the Technology'. Each party shall give reasonable notice to the other.

(2) At the request of CIMYM,  representatives  of CIM skilled in the  Technology
shall visit CIMYM's  facility to assist  CIMYM's and YM's personnel in using the
Technology.  CIMYM  shall  pay the  reasonable  disbursements  in  sending  such
representatives to CIMYM's facility.


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7. IMPROVEMENTS

All Improvements to the Technology by CIM shall be the property of CIM, shall be
disclosed to CIMYM and shall be included  within the license  granted under this
Agreement.

8. CONFIDENTIALITY OF INFORMATION

CIMYM, YM,CIM and CIMAB shall maintain the confidentiality of information, other
than its own, that is not publicly available,  including (i) the Technology, and
(ii)  information  about the businesses of the other relating to the Technology,
the Products or the  Agreement.  " YM, CIM and  CIMABshal1 not disclose any such
information,  other than its own,  to  Persons  ~J other  than  their  officers,
employees. agents, consultants and advisers, except where the disclosure of such
information by CIMYM, CIM, YM or CIMAB is to a Person who has agreed to maintain
the  confidentiality  of such  information,  or except where CIMYM,  YM, CIM and
CIMAB agree to disclose  such  information.  YM shall have the right to disclose
confidential information for the purpose of raising investment capital.

9. PRODUCT DEVELOPMENT -SUPPLY, PRE-CLINICAL, CLINICAL, COMMERCIAL

(1) CIMAB shall make its staff.  facilities  and  equipment  available to assist
CIMYM in performing its obligations under this Agreement and in  commercializing
the Products.

(2) CIMYM shall  source the Product  from CIM. If CIM does not  Manufacture  the
Product in  accordance  with the  Standards,  CIMAB  shall,  with the consent of
CIMYM,  which  shall not be withheld  unreasonably,  select  another  site which
complies with the Standards for the  Manufacture  of the Product for sale in the
Territory.  CIMAB shall grant all  necessary  licenses to other  Persons for the
Manufacture of the Product at that other site.

(3) CIMAB or its  licensed  manufacturer  shall  supply the Product to CIMYM for
pre-  clinical  and  clinical  trials at its  expense  and shall be  entitled to
recoupment of this expense as described in Article (12)(2). Before supplying the
Product,  CIMAB,  or its licensed  manufacturer,  shall perform  quality control
tests  requested by CIMYM and provide samples of the Product to CIMYM for review
within ten (10) days after the tests are  completed.  CIMYM shall  notify  CIMAB
whether the samples meet the  Standards.  Provided  that CIMAB has  Manufactured
Product that meets the Standards,  CIMYM shall,  at its own expense,  and within
time frames to be agreed upon with CIMAB.  conduct or cause to be conducted  all
further  tests  and  clinical   studies   necessary  to  enable  CIMYM  to  file
applications for regulatory approval with the appropriate regulatory authorities
in the  Territory  for the  Marketing ot tne Product.  If CIMYM fails to conduct
such tests or fails to cause such tests to be  conducted  within the time frames
agreed  upon by CIMYM and  CIMAB,  CIMAB  shall  have the right to  convert  the
exclusive  license  granted under this Agreement to a  non-exclusive  license to
CIMYM to Finish and Market the Product in the Territory  using the Technology by
providing notice in writing to CIMYM, except in those countries in the Territory
in which the Product has already been submitted for registration.

(4) CIMAB, or its licensed  manufacturer,  shall supply the Product to CIMYM for
commercial  sale at the Best  Available  Price and  shall  provide  all  quality
control tests  requested by CIMYM relating to the Product to CIMYM.  CIMYM shall
indicate to CIMAB  whether the Product  meets the  Standards.  Provided that the
Product meets the Standards,  and subject to the completion of the  pre-clinical
and clinical  trials,  CIMYM shall  Finish and Market the  Product,  acting in a
commercially reasonable manner.

(5) If CIMYM determines that any of the test results or samples of the Product ~
provided by CIMAB, whether for pre-clinical,  clinical or commercial use, do not
meet the Standards.  CIMYM may either (i) require that the Manufacture of any of
the batches of Product which do not meet the Standards be repeated within a time
frame  specified by CIMYM,  or (ii) ~c obtain the Product from a source anywhere
in the world which  Manufactures the Product in accordance with the Standards as
described in (9)(2) above.

(6) If  CIMAB  cannot  supply  the  Product,  for  commercial  use,  at the Best
Available  Price,  CIMYM may obtain the  Product  from a source  anywhere in the
world  offering  the Best  Available  Price  until such time as CIMAB is able to
supply the Product at the Best Available Price as described in (9)(2) above.


<PAGE>


(7) If CIMAB cannot supply the Product,  for any reason including force majeure,
whether for  pre-clinical,  clinical or commercial  use,  within the time-frames
specified  by CIMYM from time to time during the term of this  Agreement.  CIMYM
may obtain the Product from a source anywhere in the world,  which  Manufactures
the Product in accordance  with the time- frames,  and in accordance with (9)(2)
above.

10. RIGHT OF FIRST REFUSAL

CIMAB shall give CIMYM the right to be the first  Person to acquire a license to
Manufacture,  Finish or Market, in the Territory, any other product derived from
the EGF and EGF-R programs of CIM, except its anti-EGF-R monoclonal antibody for
psoriasis in Europe. If CIMYM waives this right.  CIMAB may enter into a licence
with another Person on the same terms as those that CIMAB offered to CIMYM or on
less favourable  terms than those that CIMAB offered to CIMYM. If CIMAB proposes
to offer the right on more  favourable  terms than the terms that CIMAB  offered
initially  to CIMYM,  CIMAB shall first  offer  those more  favourable  terms to
CIMYM.  Should CIMYM wish to acquire a license to Manufacture,  Finish or Market
that other product, CIMYM and CIMAB shall enter into a further agreement.

11 REGULATORY APPROVALS

(1)  Subject  to  Article  9,  CIMYM  shall  conduct  or cause  to be  conducted
pre-clinical  and  clinical  trials to evaluate the  Products.  CIMYM shall work
together with CIMAB to:

o     select sites in Canada for pre-clinical and clinical trials;
o     develop protocols for pre-clinical and clinical trials; and
o     instruct investigators of the pre-clinical and clinical trials

(2) Within ninety (90) days after the end of each stage of the  pre-clinical and
clinical trials of each Product. CIMYM in its discretion shall determine whether
to  proceed  with the next stage of the  trials or  whether  to  terminate  this
Agreement for that  Product,  in  accordance  with the  provisions of Article 15
after an  evaluation  of the  results by both CIMYM and  CIMAB.  CIMAB  shall be
entitled to receive the results of the preclinical and clinical trials.

(3) Where commercially reasonable,  CIMYM shall file or shall cause to be filed:
applications for regulatory approval to Market the Product in the Territory. All
applications  for regulatory  approval shall be filed in the name of CIMYM.  The
approvals shall not affect CIM's ownership of the Patents.

12. COMPENSATION FOR LICENSE

(1) YM shall,  immediately  upon receipt of evidence  satisfactory  to it of the
approval of Cuban authorities for the Agreement, incorporate a company ("CIMYM")
the issued and  outstanding  equity  voting shares of which YM shall own 80% and
CIMAB shall own 20%. CIMYM shall perform YM's  obligations  under this Agreement
and shall  not  commercialize  any  product  other  than the  Product  and other
products of CIMAB. If CIMYM defaults in performing any of its obligations  under
this Agreement. YM shall perform such obligations.

(2) Within  ninety (90) -days of the end of each calendar  quarter,  CIMYM shall
send to CIMAB a statement  certified by a financial  officer of CIMYM disclosing
the Net Revenues for the just ended calendar quarter and the compensation due to
CIMAB.  On completion of the clinical  trials CIMAB shall be reimbursed  for the
cost of the product  supplied by it for the  pre-clinical  and  clinical  trials
conducted  outside Cuba from  revenues  received by CIMYM in proportion as those
costs are to the deductions  described in the section of Definitions  describing
Net Revenues..

(3) On a schedule  to be agreed  upon in  writing  by CIMYM and CIMAB,  YM shall
advance  $2,000,000 US of operating revenue in installments from time to time to
CIMAB to support the research and  development  activities of CIM to develop the
Product for use in humans.  Of that  52,000,000 US, CIMYM shall pay to CIMAB the
following installments:

         Amount                          Date
         ------                          ----
         $100,000                 Upon the Effective Date
         $100,000                 Within 90 days of the Effective Date
         $100,000                 Within 180 days of the Effective Date
         $100,000                 Within 270 days of the Effective Date
         $300,000                 Within 18 months of the Effective Date


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         Amount                          Date
         ------                          ----
         $300,000                 Within 24 months of the Effective Date
         $300,000                 Within 30 months of the Effective Date

All of the above payments are subject to the prior  achievement of milestones to
be as established and agreed upon By CIMYM and CIMAB prior to the Effective Date
(the "Research").

If CIMYM fails to make the first four installments by the dates set out above or
in accordance  with the Research,  CIMAB shall have the right to terminate or to
convert the exclusive  license  granted under this Agreement to a  non-exclusive
license to CIMYM to Finish and Market  the  Product in the  Territory  using the
Technology by providing notice in writing to CIMYM.

If CIMYM  fails to make the  balance  of the  installments  by the dates set out
above or in accordance  with the Research  CIMAB shall have the right to convert
the exclusive license granted under this Agreement to a non-exclusive license to
CIMYM to Finish and Market the Product in the Territory using the Technology, by
providing notice in writing to CIMYM.

(4) If obliged so to do by any  applicable  tax law,  CIMYM or YM may deduct any
governmental  withholding  tax on any  payment due under this  Agreement.  CIMYM
shall provide reasonable  assistance to CIMAB in securing any benefits available
to CIMAB with respect to  governmental  tax with holdings by any relevant law or
double tax treaty.

(5) CIMYM shall keep at its registered  office full and accurate  records of the
Net Revenues. Such records shall be made available for inspection by CIMAB or an
independent  certified  public or chartered  accountant of CIMAB's choice during
normal business hours after reasonable notice.

13. PATENTS AND INFRINGEMENT

(1) If any infringement comes to the attention of CIMYM it shall promptly notify
CIMAB in writing.  If any  infringement  comes to the attention of CIMAB,  CIMAB
shall  promptly  notify CIMYM in writing.  CIMYM shall take such steps as it may
consider  advisable  against that infringement for the protection of CIMAB, CIM,
or CIMYM's  rights in the  Territory.  CIMYM shall have  exclusive  carriage and
control of any action for  infringement,  and may settle any such action without
the consent of CIMAB or CIM.  CIMYM shall  assume the cost of any such action in
the Territory. CIMYM may delegate the carriage and control of any such action to
an Affiliated Company or to a sub-licensee.

(2) If any actual or potential claim against CIMAB, CIM or CIMYM relating to the
Product comes to the attention of CIMYM,  CIMYM shall  promptly  notify CIMAB in
writing.  If any actual or potential claim against CIMAB, CIM, CIMYM relating to
the Product comes to the attention of CIMAB,  CIMAB shall promptly  notify CIMYM
in  writing.  CIMYM  shall have  exclusive  carriage  and  control of any action
brought  against  YM.  CIM,  CIMYM or CIMAB.  arising  out of CIMYM's use of the
Technology, or arising out of the Manufacturing,  Finishing or Marketing, or any
sale or offer of sale of the  Product in any country in the  Territory,  and may
settle any such action  without the consent of CIMAB or CIM.  CIMYM may delegate
the carriage and control of ~: any such action to an Affiliated  Company or to a
sub-licensee.

(3) CIMYM shall assume the expense for the filing,  prosecution  and maintenance
of all Patents in all countries in the Territory. CIMYM shall consult with CIMAB
in making any significant  decisions in the filing,  prosecution and maintenance
of the Patents.

14. ASSIGNMENT

This  Agreement  may be  assigned  by CIMAB or YM only  with the  prior  written
consent of the other. which consent shall not be unreasonably withheld.  Consent
shall not be necessary for any assignment of this Agreement.  including both the
rights and  obligations  under this Agreement.  to CIMYM.  YM shall  incorporate
CIMYM and assign this  Agreement to CIMYM  immediately  upon  conclusion of this
Agreement  and the receipt by YM of  evidence  satisfactory  to it of  necessary
approvals for this Agreement from the Government of Cuba.


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15. TERM AND TERMINATION

(1) This Agreement  becomes  effective of the date first set out above and shall
remain in full  force  and  effect  until  each  Patent  has  expired,  has been
abandoned, or has been declared invalid by a court of competent jurisdiction, or
unless terminated in accordance with the provisions of this Article.

(2) Within  ninety  (90) days  after the end of each  stage of the  pre-clinical
trials,  and ...after each stage of the clinical  trials,  CIMYM may, by written
notice,  terminate  this  Agreement in relation to any Product in any country in
the  Territory.  The  Agreement  shall  continue in  relation  to all  remaining
Products and remaining countries in the Territory.

(3) If CIMAB defaults in performing its obligations under this Agreement,  C!MYM
will inform  CIMAB in writing of the  default.  If such  default is not remedied
within  sixty (60) days CIMYM may  terminate  this  Agreement in relation to the
country and Product to which the default relates.

(4) If CIMYM defaults in performing its obligations under this Agreement,  CIMAB
..may, by written notice. terminate this Agreement in relation to the country and
Product to which  ;-,.j,  the default  relates if such  default is not  remedied
within sixty (60) days of such notice.

(5) On termination of this Agreement pursuant to subsection (3) of this Article,
CIMAB shall  transfer to CIMYM,  at no cost,  the  technology  to allow CIMYM to
Manufacture,  Finish and Market the Products in the country of the  Territory to
which the default relates.

(6) On termination of this Agreement pursuant to subsection (4) of this article,
CIMYM  shall  transfer to CIMAB the  registration  held by it for the Product in
that country in the Territory to which the default relates at no cost.

16. FORCE MAJEURE

Subject to Article 9. if any Person is unable to carry out its obligations under
this  Agreement,  acting in good faith with due diligence,  by reason of acts of
God,  war,  sabotage,  embargoes,  acts of the  public  enemy.  riot,  civil  or
political commotion,  strikes or other labour disputes.  fires. floods. or other
natural  disasters,  then the  performance  of the  obligations  of such Person.
insofar as it is affected by such cause, shall be excused during the continuance
of any such cause.

17. PROPER LAW

Any action  brought by  CIMAB.CIMYM  or by YM to enforce any  provision  of this
Agreement or alleging any breach  thereof shall be brought before the applicable
Courts of the Province of Ontario. or the Federal Court of Canada. CIMAB attorns
to the jurisdiction of the applicable Courts of the Province of Ontario.  or the
Federal Court of Canada.  This  Agreement  shall be governed by and construed in
accordance with the laws of Ontario and applicable laws of Canada.

18. COMPLIANCE WITH LAWS AND CHANGES IN LEGISLATION

CIMYM  and CIMAB  shall  perform  their  obligations  under  this  Agreement  in
compliance with all applicable laws. If national or international legislation or
other  national  or  international  rules  necessitate  changes  in the  present
Agreement  or make  it  illegal  for a  Person  to  apply  a  provision  of this
Agreement.  the Agreement  shall continue to be applied to the extent that it is
legally  possible and insofar as it is not clearly unfair to one of the parties.
Changes in the  provisions of this  Agreement that might be necessary due to the
above-mentioned  conditions  shall  be  kept to the  minimum  which  is  legally
required and to the extent  possible the changes  shall aim at  maintaining  the
contents of this Agreement as much as possible in word as well as in spirit.

19. INDEMNIFICATION BY CIMAB

(1) CIMAB shall indemnify CIMYM, YM its affiliates and sub-licensees against all
claims, damages,  liabilities,  costs and expenses,  including all counsel fees,
arising  from:

o any default or negligence of CIMAB or a licensee. or

o any allegation of injury,  damage or wrongdoing caused by the Manufacturing of
the  Product  by CIM.  or a  licensee.  or any breach of this  Agreement  or any
covenant or warranty in it by CIMAB


<PAGE>


(2) CIMAB shall use its commercially  reasonable  efforts to obtain and maintain
insurance,  naming  CIMAB,  CIM and YM in an  amount of at least  $5,000,000  US
relating to the events set out in subsection (1) of this Article,  failing which
the share of Net  Revenues  otherwise  payable to CIMAB shall be set off against
the amounts owing under this indemnity.

20. INDEMNIFICATION BY CIMYM

(1) CIMYM shall indemnify YM and CIMAB against all claims. damages, liabilities,
costs and expenses.  including all counsel fees,  arising from:

o   any  allegation  of  infringement  of  another  Person's  rights  other than
    patent  or  proprietary  rights which  were infringed by CIMAB or CIM before
    the date of execution of this Agreement, or

o   any  allegation of injury,  damage or wrongdoing  caused by the Finishing or
    Marketing  of  the  Product  by  CIMYM  ,  an  Affiliated   Company,   or  a
    sub-licensee, or

o   any default or negligence of CIMYM, or its affiliates or its  sub-licensees,
    or .any breach of this Agreement or any covenant or warranty in it by CIMYM

(2) CIMYM shall use its commercially  reasonable  efforts to obtain and maintain
insurance,  naming  CIMAB,  CIM and YM in an  amount of at least  $5,000,000  US
relating to the events set out in subsection (1) of this Article,  failing which
the share of Net  Revenues  otherwise  payable to CIMYM shall be set off against
the amounts owing under this indemnity.

21. GENERAL

(1) This  Agreement is the entire  Agreement of YM and CIMAB with respect to the
subject matter of this Agreement.

(2) No  amendment  or other  modification  of this  Agreement  shall be valid or
binding on either party to this Agreement unless reduced to writing and executed
by each of YM or CIMYM and CIMAB.

(3) Any waiver of any right under this Agreement shall be in writing.  No waiver
of any breach shall be a waiver of any subsequent breach of this Agreement.

(4) All  provisions of this  Agreement  shall be severable and no such provision
shall be affected by the  invalidity  of any other such  provision to the extent
that such invalidity does , not also render such other provision invalid.

(5) Time is of the essence of this Agreement.

(6) The use of the singular in this Agreement  shall include the plural and vice
versa.

(7) Article 2,  Article 4,  Article 8,  Article 17,  Article 19,  Article 20 and
Article 21 shall survive the termination of this Agreement.

(8) All  information  required  to be  provided  to CIMYM  by the  terms of this
Agreement shall, if necessary, be translated into the English language.

(9)  There  shall  be a  shareholders'  agreement  relating  to the  rights  and
obligations of the shareholders.  This agreement shall include an agreement that
the board of YM shall only permit the transfer of shares of YM which result in a
single shareholder, or group of shareholders acting in concert, owning more than
50% of the voting  shares,  by  unanimous  agreement.  The  articles of YM shall
ensure that there shall be at least one member of the board of  directors  of YM
who shall be appointed by those Cuban  interests with whom, YM has joint venture
agreements.


<PAGE>


10) YM shall receive, in a form satisfactory to it, written evidence that all of
the  provisions of this  Agreement are legal and  enforceable  under the laws of
Cuba and that if any action were to be brought by YM to enforce any provision of
this Agreement or alleging any breach thereof in the applicable  Courts of Cuba,
in the  absence of  Article 17 of this  Agreement,  such  Courts  would have the
ability to enforce all of the provisions of this Agreement.

YM shall  receive,  in a form  satisfactory  to it,  evidence  of all  necessary
approvals of this ~ Agreement from the applicable Cuban authorities.

YM shall receive.  in a form satisfactory to it, evidence that the Government of
Cuba has permitted the execution of this Agreement.

YM shall,  immediately upon receipt of the evidences and assurances sought by it
in Article(21 )(1 0), notify CIMAB in writing.

22. NOTICE

Any notice  required to be given  pursuant to the  provisions of this  Agreement
shall be in writing and shall be delivered  personally sent by facsimile or sent
by registered or certified mail (return receipt requested),  postage prepaid, to
the  address  and  facsimile  numbers  identified  on the  first  page  of  this
Agreement.  Such notice  shall be  effective on the date that it is delivered or
sent by facsimile or in the case where notice is sent by registered or certified
mail,  on the seventh  business  day after the notice is so sent.  Any party may
change its address for service by sending a notice in accordance  with the terms
of this section of the Agreement.


SIGNED FOR
YORKTON MEDICAL INC.

DATE:

By:  "David GP Allan"
   -----------------------
   Name David G. P. Allan
   Title: Chairman


SIGNED FOR CIMAB S.A.

DATE:

By: "Patricia Sierra"
    ----------------------
Name : Patricia Sierra
Title: President ;



CIM,agt.28.Apr.95


<PAGE>


                                   SCHEDULE 1

Patents,  Patent Applications and Invention Disclosures filed in each country in
the Territory and relating to Products

<TABLE>
<CAPTION>
<S>                      <C>                           <C>
+-----------------------+-----------------------------+-----------------------------------------------------+
| PATENT APPLICATIONS   | TERRITORY                   | RELATED PRODUCTS                                    |
+-----------------------+-----------------------------+-----------------------------------------------------+
| EP93202428.4          | EPO:Designed States:        | Murine ior rgf/3r:                                  |
|                       | Austria                     |                                                     |
|                       | Belgium                     | -        99m Tc-ior egf/3r                          |
|                       | Switzerland                 | -        99m Tc-ior egf/3r Cold Kit                 |
|                       | Germany                     | -        Therapeutic for egf/3r                     |
|                       | Spain                       | -        ior egf/r4/GM3 combination                 |
|                       | France                      |                                                     |
|                       | England                     |                                                     |
|                       | Greece                      | Monoclonal anti-bodies against EGF (murine) and     |
|                       | Italy                       | for egf/r3 combination                              |
|                       | Liechtenstein               |                                                     |
|                       | Lusemburg                   |                                                     |
|                       | Monaco                      |                                                     |
|                       | Holland                     |                                                     |
|                       | Portugal                    |                                                     |
|                       | Sweden                      |                                                     |
|                       | Iceland                     |                                                     |
| P69/93                | Canada                      |                                                     |
+-----------------------+-----------------------------+-----------------------------------------------------+
|                       | Cuba                        | Humanized ior egf/r3                                |
+-----------------------+-----------------------------+-----------------------------------------------------+
</TABLE>


<PAGE>
















                       SCHEDULE 2 N/A NO LONGER APPLICABLE


















<PAGE>


                                   SCHEDULE 3

                      SPECIFICATIONS SCHEDULE FOR PRODUCTS

<TABLE>
<CAPTION>
<S>                                      <C>
+---------------------------------------+-------------------------------------------------------------------------+
|                   PRODUCTS            |               FEATURES                                                  |
+---------------------------------------+-------------------------------------------------------------------------+
| 99mTc-ior egf/r3 Cold Kit             | Murine  MoAb   against   EGF-Receptor,   labeled  with radioactive      |
|                                       | technetium.  It labels epidermoid carcinomas in vivo to be detected     |
|                                       |  in Gamma Camera.                                                       |
+---------------------------------------+-------------------------------------------------------------------------+
| Therapeutic ior egf/3r                | Murine MoAb against EGF-receptor.                                       |
+---------------------------------------+-------------------------------------------------------------------------+
| Ior egf/r3/GM3 Combination            | Evidence  gathered in the  potentiation  between jor egf/r3 and the     |
|                                       | GM3, in the  inhibition  of monosialoganglioside tumor cell             |
|                                       | proliferation in vitro and in laboratory animals.                       |
+---------------------------------------+-------------------------------------------------------------------------+
| Humanized-ior egf/r3                  | Recombinant  MoAb against EGF-R. It keeps murine,  sequences only       |
|                                       | in heavy chain CaRs and 3 murine substitutions in the frameworks,       |
|                                       | all the rest of the molecule is human.  It retains 100%  affinity       |
|                                       | as comparedwith the murine MoAb.                                        |
+---------------------------------------+-------------------------------------------------------------------------+
| Monoclonal Antibody against EFG       | Murine MoAb  recognizing  human EGF and inhibiting EGF binding to       |
|                                       | its receptor.                                                           |
+---------------------------------------+-------------------------------------------------------------------------+
</TABLE>


<PAGE>


                                  AMENDMENT TO

                           LICENSING AGREEMENT BETWEEN

                            CIMAB S.A. AND CIMYM INC

                                DATED MAY 3,1995

                            "RADIOTHERACIM AMENDMENT"

                                                                September 3 1998

         CIMAB S.A.  (CIMAB) and York Medical  Inc.  (YM) entered into a licence
agreement dated May 3, 1995 (the "Licence  Agreement") for products described in
that agreement as the  "Products".  On November 24, 1995, YM assigned its rights
under that agreement to CIMYM.

By this agreement,

1. CIMAB and CIMYM amend the definition of, 'Product" in that Licence  Agreement
to add a radio  immunotherapeutic  Product against EGF-R including the humanized
monoclonal antibody "R3".

2.  The  product  being  added  to the  Licence  Agreement  shall  be  known  as
"RadioTheraCim".

3.  RadioTheraCim  shall be developed by CIMYM in  accordance  with the workplan
("Workplan") attached to this Amendment as an appendix (the "Appendix").

4. The payments described in the Appendix  (US$330,000)shall be payable by CIMYM
to CIMAB for research relating to the development of  RadioTheraCim,  subject to
satisfactory progress of the Workplan, the research and development described in
the Workplan and the viability of the project.

5. For calendar  1999 and 2000,  the  quarterly  amounts for  RadioTheraCim  are
payable in the first month of each quarter.

6. The payments  described in the Appendix relate to CIMYM's  obligations  under
this amending  agreement.  The payments described in the Appendix for DiaCIM and
TheraCIM  relate to CIMYM's  obligations  under  section  12(3) of the Licensing
Agreement, as amended.

7.  Termination  of payments by CIMYM in  relation to anyone  Product  shall not
affect CIMYM's rights in relation to the other Products.

8. If CIMYM  fails to make the  payment  for any Product by the dates set out in
the Appendix,  CIMAB's sale remedy is to convert the exclusive  license for that
Product to a non-exclusive  license or to terminate the grant of rights relating
to that Product.  9. In all other respects,  the terms of the License  Agreement
govern.

This Amendment is effective April 1, 1997

Signed for CIMYM INC.                           Signed for CIMAB S.A.

By: "David GP Allan"                            By: "Patricia Sierra"
    -----------------------                         -------------------------
Name: David GP Allan                            Name: Patricia Sierra
Title: Director                                 Title: President
Date: Sept. 13, 1998                            Date: Sept. 18, 1998



<PAGE>


                                  WORK SCHEDULE

                        RELATED TO PAYMENTS DESCRIBED IN

                           "APPENDIX TO RADIOTHERACIM

                         AMENDMENT OF SEPTEMBER 3, 1998"

<TABLE>
<CAPTION>
<S>                                                      <C>        <C>        <C>       <C>        <C>       <C>
+-------------------------------------------------------+----------+----------+---------+---------+----------+------------+
|                                                       |          |          |  First  |  Second |  Third   |            |
|               Task Name                               |  Start   |   End    |  Year   |  Year   |  Year    |   Total    |
+-------------------------------------------------------+----------+----------+---------+---------+----------+------------+
|                                                       |          |          |         |         |          |            |
|A. Radiochemical Experiments                           |          |          |  25 000 | 25 000  |  30 000  |   80 000   |
|1. Optimization of labeling conditions                 | Month  1 | Month  3 |         |         |          |            |
|2. Establishment of the freeze-dried kit information   | Month  1 | Month  9 |         |         |          |            |
+-------------------------------------------------------+----------+----------+---------+---------+----------+------------+
|B. Pilot Scale Production                              |          |          |         |         |          |            |
|1. Production of 9 grams of humanized mAb R3           | Month  1 | Month  5 |  15 000 | 15 000  |  20 000  |   50 000   |
|2. Production  of three lots of humanized  mAb R3 in a |          |          |         |         |          |            |
|   freeze-dried kit formulation                        | Month  6 | Month  9 |  15 000 | 15 000  |  20 000  |   50 000   |
|o  Production of the first lot                         |          |          |         |         |          |            |
|o  Production of the second lot                        | Month  6 | Month  7 |         |         |          |            |
|o  Production of the third lot                         | Month  7 | Month  8 |         |         |          |            |
|                                                       | Month  8 | Month  9 |         |         |          |            |
|3. Production Shelf study of humanized mAb R3 in a     |          |          |         |         |          |            |
|   freez-dried kit formulation (one and a half year)   | Month  7 | Month 25 |  10 000 | 10 000  |  10 000  |   30 000   |
+-------------------------------------------------------+----------+----------+---------+---------+----------+------------+
|C. Preclinical Studies                                 | Month  1 | Month 18 |  15 000 | 15 000  |  10 000  |   40 000   |
|1. Further studies of humanized mAb   R3               | Month  7 | Month 11 |         |         |          |            |
|o  Acute toxicology                                    | Month 10 | Month 12 |         |         |          |            |
|o  Subchronic toxicology                               |          |          |         |         |          |            |
|2. Pharmacokinetics  and  biodistribution  in  rats at | Month  3 | Month  8 |         |         |          |            |
|   different doses                                     |          |          |         |         |          |            |
|3. Pharmacokinetics  and  biodistribution  in  moneys  | Month  3 | Month  6 |         |         |          |            |
|4. Therapeutic effects in a xenograft model of tumor   |          |          |         |         |          |            |
|   from epithelial origin                              | Month  4 | Month 18 |         |         |          |            |
+-------------------------------------------------------+----------+----------+---------+---------+----------+------------+
|D. Clinical Studies                                    |          |          |      -- | 20 000  |  60 000  |   80 000   |
|1. Protocol Draft for a Phase I Clinical Trial         | Month 18 | Month 22 |         |         |          |            |
|2. Clinical Trial Phase I/II                           | Month 23 | Month 36 |         |         |          |            |
|3. Report of Clinical Trial Results                    | Month 36 | Month 38 |         |         |          |            |
+-------------------------------------------------------+----------+----------+---------+---------+----------+------------+
|Total                                                  |          |          |  80 000 | 100 000 |  150 000 |  330 000   |
+-------------------------------------------------------+----------+----------+---------+---------+----------+------------+
</TABLE>


<PAGE>


                                  AMENDMENT TO
                               LICENSING AGREEMENT
                                     BETWEEN
                            CIMAB S.A. AND CIMYM INC.
                                DATED MAY, 1995.


                                                                September 3 1998

CIMAB S.A.  (CIMAB)  and CIMYM INC.  (CIMYM)  recognize  that under a  Licensing
Agreement  dated May 3, 1995,  as amended,  (the  Agreement)  clause 12.3 of the
Agreement  states that York Medical  INC.  (YM) shall  advance to CIMAB  through
CIMYM US$2 million to support  research and development  activities of Centro de
Inmulogia Molecular (CIM) as compensation for the license (the  "Compensation").
On November 24, 1995, YM assigned its rights under the Agreement to CIMYM.  As a
result of the meeting of August 19, 1998 between CIMAB, CIMYM, YM and CIM it was
agreed to amend the Agreement as follows:

1)  Clause  12.3  of  the  Agreement  states  that  US$1.3  million  USD  of the
Compensation  would be paid to CIMAB upon the achievement of certain  milestones
(defined therein as the Research) to be agreed upon by CIMYM and CIMAB.

Of the US$1.3  million,  US$1  million  has been paid and  received by CIMAB and
US$300,000 is still to be paid upon the  achievement  of certain  milestones for
the  diagnostic  Product  "DiaCim"  and  the  therapeutic   Product  "TheraCim".
Effective with the,  signing of this Amendment the US$300,  000 shall be paid as
follows:

a)  US$150,OOO  upon the approval of the  Investigational  New Drug  Application
(IND) by the Health  Protection  Branch,  Canada  (HPB) for DiaCim for a Phase 1
trial in Canada.

b) US$150,OOO  upon the approval by the HPB of an IND for TheraCim for a Phase I
trial in Canada.

The payments  referred to in a) and b) above are listed in the attached schedule
(" Appendix to Amendment to Licensing  Agreement of May 1995,  dated September 3
1998") under the columns  headed  "TheraCIM"  and "DiaCIM".

2) Of the remaining US$700,000 of Compensation, whose payment has not previously
been defined,  it is agreed by this Amendment that an amount of US$225,00O is to
be paid for the progression of the TheraCim project in quarterly amounts of US$3
7,500 in the first month of each quarter,  the first quarter  beginning  July I,
1998, subject to satisfactory progress in the research.  The scheduling of these
payments is listed in the attached schedule ("Appendix to Amendment to Licensing
Agreement  of May  1995,  dated  September  3 1998")  under  the  column  headed
"TheraCIM".

Terms for payment of the balance of the Compensation,  being US$475,OOO,  remain
to be determined  between CIMYM and CIMAB and is listed in the attached schedule
("Appendix to Amendment to Licensing  Agreement of May 1995,  dated  September 3
1998") under the columns headed "TheraCIM" and "DiaCIM".

This  Amendment  confirms  the  agreement  that the amounts due up to the period
ended  June 30,  1998 have been  paid to or on  behalf of CIMAB,  except  for an
amount remaining amount of US$500. This deferred payment of US$500 does not give
CIMAB any right to convert the exclusive  license to a non-exclusive  license or
to terminate the license under  sections  12(3) of the  Agreement.  In all other
respects, the terms of the Agreement govern.

SIGNED FOR                                           SIGNED FOR
CIMYM INC.                                           CIMAB S.A.
Date:  Sept. 18, 1998                                Date:  Sept. 18, 1998
By:    "David GP Allan"                              By:    "Patricia Sierra"
       ------------------                                   --------------------
Name:  David GP Allan                                Name:  Patricia Sierra
Title: Director                                      Title: President

<PAGE>


                               THIRD AMENDMENT TO
                               LICENSING AGREEMENT
                                     BETWEEN
                            CIMAB S.A. AND CIMYM INC.
                               DATED MAY 3, 1995.


CIMYM INC., a corporation incorporated under the laws of the Province of Ontario
and located at 5045 Orbitor Drive, Mississauga,  Ontario, Canada and CIMYM INC.,
a corporation incorporated under the laws of Barbados and located at The Life of
Barbados  Building,  Wildey,  St. Michael,  Barbados  (together referred in this
Amendment Agreement as "CIMYM")


AND

CIMAB S.A., a corporation  incorporated  under the laws of Cuba,  located at 206
St., No. 1926, between 19 and 21, Atabey, Havana, Cuba ("CIMAB").

WHEREAS:

A. CIMAB and CIMYM signed a Licensing  Agreement  dated May 3, 1995, as amended,
(hereinafter referred to as the" Agreement"). ,

B. All defined terms used in this amendment agreement  (hereinafter  referred to
as "this  Amendment  Agreement"  have the same  meaning as that set forth in the
Agreement.

C. In the  Agreement,  CIMAB granted to CIMYM the exclusive  right to Finish and
Market the Product using the Technology.

D. Article 12.3 of the Agreement states that CIMYM shall advance $ 2,000,000 USD
to support the research and development activities to develop the Product for in
humans.

E. CIMYM has paid the aforementioned $ 2,000,000 USD.

F. The parties wish to develop a new production process in order to increase the
value  of  the  Product  for   sub-licenses  to  be  granted  by  CIMYM  to  its
sub-licensees.

G.  Article  12.1 of the  Agreement  states  that CIMAB shall own 20% of CIMYM's
shares as compensation  for the License.  Article 12.2 states that within ninety
(90)  days of the end of each  calendar  quarter,  CIMYM  shall  send to CIMAB a
statement  certified,  disclosing the Net Revenues and the  compensation  due to
CIMAB.

H.  Notwithstanding  these  Articles  of the  Agreement,  both  parties  wish to
increase  CIMAB's  compensation  payable  under the  Agreement  in exchange  for
certain concessions by CIMAB.

I. In the Agreement, Net Revenues means the total of all money received by CIMYM
from sales of the Product and from rights to Finish or Market the Product in the
Territory  less  certain  operating  expenses,  as  defined  in  the  Agreement,
associated with the commercialization of the Product.


<PAGE>


J. According to the  definition of Net Revenues in the Agreement,  neither party
can obtain any revenues  until all the expenses of CIMYM advanced for it by York
Medical and  relating to the  Product are netted from the  revenues  and paid to
York Medical.

K. The  parties  wish to modify the  Agreement  in order (i) that CIMAB  obtains
certain revenues before all the operating  expenses of CIMYM are netted from the
revenues,  and (ii) to include in the  definition  of  "operating  expenses" the
expenses relating to all Products licensed by CIMAB to CIMYM under the Agreement
and under the Licensing Agreement dated December, 1997.

L. CIMAB wishes to fix a price at which  Product  manufactured  by CIMAB will be
sold to CIMYM so that  CIMYM can obtain a margin of  revenues  from the sales of
the Product.

M.  Articles  9.3 and 9.4 of the  Agreement  state that CIMAB  shall  supply the
Product to CIMYM for pre-clinical and clinical trials,  and for commercial sale.
However,  there are  numerous  prospective  sub-licensees  that  will  insist on
manufacturing  the  Product  themselves  or through  their own  contractors  and
sub-contractors.  .' N. The definition of Territory  includes certain  countries
but not all countries of the world and the prospective  sublicensees may wish to
include in the sub-license agreements all or certain other countries.

           FOR VALUABLE CONSIDERATION, THE RECEIPT AND SUFFICIENCY OF
           WHICH THE PARTIES ACKNOWLEDGE, THE PARTIES AGREE AS FOLLOW:

1. CIMYM shall advance $ 750, 000 USD, from time to time during the term ()f the
Agreement as required, in order to develop the manufacturing of the Product to a
30 liter scale.  As of July 1, 2000 CIMYM has advanced to CIMAB $ 250,000 USD of
this $ 750,000  USD.  CIMYM and CIMAB shall  jointly  determine  how to best use
these funds to develop the manufacture of the Product to the 30 liter scale.

2.  CIMYM,  by  consensus,   shall  determine  the  timing  and  amount  of  the
installments of this $ 750,000 USD and the timing and amount of the installments
shall be reflected in a document, duly signed by CIMYM and CIMAB.

3. The Parties agree to modify Article 12.2 of the Agreement to compensate CIMAB
for rights granted under this Amending Agreement. CIMAB shall now receive 30% of
CIMYM's Net Revenues.  This 30% shall be  represented by a payment of 10% of Net
Revenues  and 20% of the  equity  of  CIMYM.  Article  12.2,  from  the  date of
signature of this Amendment will state the following:

Within ninety (90) days of the end of each calendar  quarter  during the term of
the  Agreement,  CIMYM shall send to CIMAB a statement  certified by a financial
officer of CIMYM disclosing the Net Revenues for the just ended calendar quarter
and the  compensation  due to CIMAB,  which shall be 10% of the Net  Revenues in
addition its 20% equity interest.  On completion of the clinical  trials,  CIMAB
shall be reimbursed for the cost of the Product  supplied by it to CIMYM for the
pre clinical and clinical trials conducted  outside of Cuba. The expenses of the
Product supplied by CIMAB shall be netted from revenues received by CIMYM as one
of the deductions from revenues set forth in the definition of "Net Revenues" in
the Agreement.

4. YM shall have the right to recover all money  advanced to CIMYM on account of
expenses and associated with the research,  development and commercialization of
all  Products  that CIMAB has licensed to CIMYM to the date of execution of this
Amending  Agreement.  For greater  certainty,  these  expenses shall include all
expenses associated with the research,  development and commercialization of the
EGF cancer Vaccine and  monoclonal  antibody  against EGF-r.  For as long as Net
Revenues  are less than or equal to the amount of advances  from York Medical to
CIMYM, York Medical shall recover such advances from 30% of Net Revenues and the
remaining 70% of the :; Net Revenues shall be retained by CIMYM.

5. Having  regard to this  Amending  Agreement,  the parties agree to delete the
definition  "Net  Revenues" in the  Agreement  and replace it with the following
definition:


<PAGE>


NET REVENUES  -means the total of all money  received by CIMYM from sales of the
Product and from rights to Finish or Market the  Product in the  Territory  less
operating  expenses  associated with the  commercialization  of all the Products
licensed by CIMAB to CIMYM to the date of execution of this Amending  Agreement,
including the following:  (i) pre-clinical and clinical trial costs, (ii) sales,
general and  administrative  costs, (iii) costs of goods sold, where expenditure
is applicable,  (iv) research and development costs, (v) interest  expenses,  if
any, (vi) capital expenditures (vii) the- costs of the Product supplied by CIMAB
to CIMYM for the  pre-clinical  and clinical trials  conducted  outside of Cuba.
Money received means money  received less trade-  allowances,  credit or refunds
for returned or defective Product, and allowances for doubtful debts.

However,  during the period that CIMYM's  revenues are less than or equal to the
total of  expenses to be  recouped,  only 30% of the  revenues  shall be used to
repay advances from York Medical.

6. CIMAB shall sell the Product  manufactured  by CIMAB in Cuba to CIMYM, at 85%
of the sales price that CIMYM sets for the sale of the Product to a sub-licensee
in the Territory.

7. CIMYM shall use its best efforts to obtain a  sub-license  agreement in which
CIMAB retains the right to manufacture the Product.  However, if the sublicensee
insists  on  manufacturing  the  Product  itself,  through  its  contractors  or
sub-contractors,  CIMAB shall waive its  manufacturing  rights,  if both parties
consider that sub-license agreement offers mutual favorable commercial terms.

8. If a sub-licensee  insists on including new territories  (not  encompassed by
the defmition of "Territories")  in the Agreement,  the parties shall assess the
feasibility of including those  territories in the  sub-license.  If the parties
amend  this  Agreement  to  include  additional  territories  so that  CIMYM can
sub-license  those  additional  territories,  the parties  shall  detennine  the
additional  compensation  payable to CIMAB for the  inclusion of the  additional
territories.

9. CIMAB represents and warrants that CIMAB shall not negotiate unilaterally any
territories  not  encompassed by the defmition of Territory with any prospective
sublicensee with whom CIMYM is negotiating for a sub-license.

AND IN WITNESS WHEREOF, the parties execute this Amendment Agreement on the date
set out below.

SIGNED FOR                                           SIGNED FOR
CIMYM INC.                                           CIMAB S.A.
Date:  May 31, 2000                                  Date:  May 31, 2000
By:    "David GP Allan"                              By:    "Patricia Sierra"
       ----------------------                               --------------------
Name:  David GP Allan                                Name:  Patricia Sierra
Title: Director                                      Title: President


<PAGE>


                               FOURTH AMENDMENT TO
                               LICENSING AGREEMENT
                                     BETWEEN
                            CIMAB S.A. AND CIMYM INC.
                               DATED MAY 3, 1995.

CIMYM INC., a corporation incorporated under the laws of the Province of Ontario
and located at 5045 Orbitor Drive, Mississauga,  Ontario, Canada and CIMYM INC.,
a corporation incorporated under the laws of Barbados and located at The Life of
Barbados  Building,  Wildey,  St. Michael,  Barbados  (together referred in this
Amendment Agreement as "CIMYM")


AND

CIMAB S.A., a corporation  incorporated  under the laws of Cuba,  located at 206
St., No. 1926, between 19 and 21, Atabey, Havana, Cuba ("CIMAB").

WHEREAS:

A. CIMAB and CIMYM signed a Licensing  Agreement  dated May 3, 1995, as amended,
(hereinafter referred to as the" Agreement"). ,

B. All defined terms used in this amendment agreement  (hereinafter  referred to
as "this  Amendment  Agreement"  have the same  meaning as that set forth in the
Agreement.

C. CIMAB has filed a new patent application with claims the combination  therapy
of the  Products  defined in the  Agreement  and the EGF  Cancer  Vaccine of the
Licensing Agreement signed on December 1997.

FOR VALUABLE  CONSIDERATION,  THE RECEIPT' AND  SUFFICIENCY OF WHICH THE PARTIES
ACKNOWLEDGE, THE PARTIES AGREE AS FOLLOW:

1. Modify the  Patents  definition  of the  Agreement,  which,  from the date of
signature of this Amendment Agreement will state the following:

"Patents means all patents,  patent applications and other intellectual property
rights relating to the Products and includes the patents and patent applications
identified in Schedule 1 and patent application claiming the combination therapy
of the Product and EGF based Cancer Vaccine of the Licensing Agreement signed on
December 1997".

AND IN WITNESS WHEREOF, THE PARTIES EXECUTE THIS AMENDMENT AGREEMENT ON THE DATE
SET OUT BELOW.

SIGNED FOR                                           SIGNED FOR
CIMYM INC.                                           CIMAB S.A.
Date:  February 7,2001                               Date:  February 7, 2001
By:    "David GP Allan"                              By:    "Patricia Sierra"
       ----------------------                               --------------------
Name:  David GP Allan                                Name:  Patricia Sierra
Title: Director                                      Title: President


<PAGE>


                               FOURTH AMENDMENT TO
                               LICENSING AGREEMENT
                                     BETWEEN
                            CIMAB S.A. AND CIMYM INC.
                               DATED MAY 3, 1995.

CIMYM INC., a corporation incorporated under the laws of the Province of Ontario
and located at 5045 Orbitor Drive, Mississauga, Onotario, Canada and CIMYM INC.,
a corporation incorporated under the laws of Barbados and located at The Life of
Barbados  Building,  Wildey,  St. Michael,  Barbados  (together referred in this
Amendment Agreement as "CIMYM")


AND

CIMAB S.A., a corporation  incorporated  under the laws of Cuba,  located at 206
St., No. 1926, between 19 and 21, Atabey, Havana, Cuba ("CIMAB").

WHEREAS:

A. CIMAB and CIMYM signed a Licensing  Agreement  dated May 3, 1995, as amended,
(hereinafter referred to as the" Agreement").

B. All defined terms used in this amendment agreement  (hereinafter  referred to
as "this  Amendment  Agreement"  have the same  meaning as that set forth in the
Agreement.

C. CIMAB has filed a new patent application with claims the combination  therapy
of the  Products  defined in the  Agreement  and the EGF  Cancer  Vaccine of the
Licensing Agreement signed on December 1997.

           FOR VALUABLE CONSIDERATION, THE RECEIPT. AND SUFFICIENCY OF

           WHICH THE PARTIES ACKNOWLEDGE, THE PARTIES AGREE AS FOLLOW:

1. Modify the  Patents  definition  of the  Agreement,  which,  from the date of
signature of this Amendment Agreement will state the following:

"Patents means all patents,  patent applications and other intellectual property
rights relating to the Products and includes the patents and patent applications
identified in Schedule 1 and patent application claiming the combination therapy
of the Product and EGF based Cancer Vaccine of the Licensing Agreement signed on
December 1997".

AND IN WITNESS WHEREOF, the parties execute this Amendment Agreement on the date
set out below.


SIGNED FOR                                           SIGNED FOR
CIMYM INC.                                           CIMAB S.A.
DATE:  Feb 7, 2001                                   DATE:  Feb 7, 2001
By:    "David GP Allan"                              By:    "Patricia Sierra"
       ----------------------                               --------------------
Name:  David GP Allan                                Name:  Patricia Sierra
Title: Director                                      Title: President